Coming Soon: Dinners

Details DinnerID: " + id + "

element to render them instead of a table using the code below:

Upcoming Dinners

<% foreach (var dinner in Model) { %>
• <%= Html.Encode(dinner.Title) %> on <%= Html.Encode(dinner.EventDate.ToShortDateString())%> @ <%= Html.Encode(dinner.EventDate.ToShortTimeString())%>
<% } %>


Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

Page 61 of 186

We are using the "var" keyword within the above foreach statement as we loop over each dinner in our Model. Those unfamiliar with C# 3.0 might think that using “var” means that the dinner object is latebound. It instead means that the compiler is using type-inference against the strongly typed “Model” property (which is of type “IEnumerable”) and compiling the local “dinner” variable as a Dinner type – which means we get full intellisense and compile-time checking for it within code blocks:

When we hit refresh on the /Dinners URL in our browser our updated view now looks like below:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

Page 62 of 186

This is looking better – but isn’t entirely there yet. Our last step is to enable end-users to click individual Dinners in the list and see details about them. We’ll implement this by rendering HTML hyperlink elements that link to the Details action method on our DinnersController. We can generate these hyperlinks within our Index view in one of two ways. The first is to manually create HTML elements like below, where we embed <% %> blocks within the HTML element:

An alternative approach we can use is to take advantage of the built-in "Html.ActionLink()" helper method within ASP.NET MVC that supports programmatically creating an HTML element that links to another action method on a Controller: <%= Html.ActionLink(dinner.Title, "Details", new { id=dinner.DinnerID }) %>

The first parameter to the Html.ActionLink() helper method is the link-text to display (in this case the title of the dinner), the second parameter is the Controller action name we want to generate the link to (in this case the Details method), and the third parameter is a set of parameters to send to the action (implemented as an anonymous type with property name/values). In this case we are specifying the “id” parameter of the dinner we want to link to, and because the default URL routing rule in ASP.NET MVC is "{Controller}/{Action}/{id}" the Html.ActionLink() helper method will generate the following output: .NET Futures

For our Index.aspx view we’ll use the Html.ActionLink() helper method approach and have each dinner in the list link to the appropriate details URL: Upcoming Dinners

Upcoming Dinners



Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

Page 63 of 186


<% foreach (var dinner in Model) { %>
• <%= Html.ActionLink(dinner.Title, "Details", new { id=dinner.DinnerID }) %> on <%= Html.Encode(dinner.EventDate.ToShortDateString())%> @ <%= Html.Encode(dinner.EventDate.ToShortTimeString())%>
<% } %>


And now when we hit the /Dinners URL our dinner list looks like below:

When we click any of the Dinners in the list we’ll navigate to see details about it:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

Page 64 of 186

Convention-based naming and the \Views directory structure ASP.NET MVC applications by default use a convention-based directory naming structure when resolving view templates. This allows developers to avoid having to fully-qualify a location path when referencing views from within a Controller class. By default ASP.NET MVC will look for the view template file within the \Views\[ControllerName]\ directory underneath the application. For example, we’ve been working on the DinnersController class – which explicitly references three view templates: “Index”, “Details” and “NotFound”. ASP.NET MVC will by default look for these views within the \Views\Dinners directory underneath our application root directory:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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Notice above how there are currently three controller classes within the project (DinnersController, HomeController and AccountController – the last two were added by default when we created the project), and there are three sub-directories (one for each controller) within the \Views directory. Views referenced from the Home and Accounts controllers will automatically resolve their view templates from the respective \Views\Home and \Views\Account directories. The \Views\Shared subdirectory provides a way to store view templates that are re-used across multiple controllers within the application. When ASP.NET MVC attempts to resolve a view template, it will first check within the \Views\[Controller] specific directory, and if it can’t find the view template there it will look within the \Views\Shared directory. When it comes to naming individual view templates, the recommended guidance is to have the view template share the same name as the action method that caused it to render. For example, above our “Index” action method is using the “Index” view to render the view result, and the “Details” action method is using the “Details” view to render its results. This makes it easy to quickly see which template is associated with each action. Developers do not need to explicitly specify the view template name when the view template has the same name as the action method being invoked on the controller. We can instead just pass the model

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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object to the “View()” helper method (without specifying the view name), and ASP.NET MVC will automatically infer that we want to use the \Views\[ControllerName]\[ActionName] view template on disk to render it. This allows us to clean up our controller code a little, and avoid duplicating the name twice in our code: public class DinnersController : Controller { DinnerRepository dinnerRepository = new DinnerRepository(); // // GET: /Dinners/ public ActionResult Index() { var dinners = dinnerRepository.FindUpcomingDinners().ToList(); return View(dinners); } // // GET: /Dinners/Details/2 public ActionResult Details(int id) { Dinner dinner = dinnerRepository.GetDinner(id); if (dinner == null) return View("NotFound"); else return View(dinner); } }

The code above is all that is needed to implement a nice Dinner listing/details experience for the site.

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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Create, Update, Delete Form Scenarios

We’ve introduced controllers and views, and covered how to use them to implement a listing/details experience for Dinners on site. Our next step will be to take our DinnersController class further and enable support for editing, creating and deleting Dinners with it as well.

URLs handled by DinnersController We previously added action methods to DinnersController that implemented support for two URLs: /Dinners and /Dinners/Details/[id]. URL

VERB

Purpose

/Dinners/

GET

Display an HTML list of upcoming dinners.

/Dinners/Details/[id]

GET

Display details about a specific dinner.

We will now add action methods to implement three additional URLs: /Dinners/Edit/[id], /Dinners/Create, and /Dinners/Delete/[id]. These URLs will enable support for editing existing Dinners, creating new Dinners, and deleting Dinners. We will support both HTTP GET and HTTP POST verb interactions with these new URLs. HTTP GET requests to these URLs will display the initial HTML view of the data (a form populated with the Dinner data in the case of “edit”, a blank form in the case of “create”, and a delete confirmation screen in the case of “delete”). HTTP POST requests to these URLs will save/update/delete the Dinner data in our DinnerRepository (and from there to the database). URL

VERB

Purpose

/Dinners/Edit/[id]

GET

Display an editable HTML form populated with Dinner data.

POST

Save the form changes for a particular Dinner to the database.

GET

Display an empty HTML form that allows users to define new Dinners.

POST

Create a new Dinner and save it in the database.

GET

Display a confirmation screen that asks the user whether they want to delete the specified dinner.

POST

Deletes the specified dinner from the database.

/Dinners/Create

/Dinners/Delete/[id]

Let’s begin by implementing the “edit” scenario.

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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Implementing the HTTP-GET Edit Action Method We’ll start by implementing the HTTP “GET” behavior of our edit action method. This method will be invoked when the /Dinners/Edit/[id] URL is requested. Our implementation will look like: // // GET: /Dinners/Edit/2 public ActionResult Edit(int id) { Dinner dinner = dinnerRepository.GetDinner(id); return View(dinner); }

The code above uses the DinnerRepository to retrieve a Dinner object. It then renders a View template using the Dinner object. Because we haven’t explicitly passed a template name to the View() helper method, it will use the convention based default path to resolve the view template: /Views/Dinners/Edit.aspx. Let’s now create this view template. We will do this by right-clicking within the Edit method and selecting the “Add View” context menu command:

Within the “Add View” dialog we’ll indicate that we are passing a Dinner object to our view template as its model, and choose to auto-scaffold an “Edit” template:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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When we click the “Add” button, Visual Studio will add a new “Edit.aspx” view template file for us within the “\Views\Dinners” directory. It will also open up the new “Edit.aspx” view template within the codeeditor – populated with an initial “Edit” scaffold implementation like below:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

Page 70 of 186

Let’s make a few changes to the default “edit” scaffold generated, and update the edit view template to have the content below (which removes a few of the properties we don’t want to expose): Edit: <%=Html.Encode(Model.Title) %>

Edit Dinner

<%= Html.ValidationSummary("Please correct the errors and try again.") %> <% using (Html.BeginForm()) { %>

Dinner Title: <%= Html.TextBox("Title") %> <%= Html.ValidationMessage("Title", "*") %>

Event Date: <%= Html.TextBox("EventDate", String.Format("{0:g}", Model.EventDate)) %> <%= Html.ValidationMessage("EventDate", "*") %>

Description: <%= Html.TextArea("Description") %> <%= Html.ValidationMessage("Description", "*")%>

Address: <%= Html.TextBox("Address") %> <%= Html.ValidationMessage("Address", "*") %>

Country: <%= Html.TextBox("Country") %> <%= Html.ValidationMessage("Country", "*") %>

Contact Phone #: <%= Html.TextBox("ContactPhone") %> <%= Html.ValidationMessage("ContactPhone", "*") %>

Latitude: <%= Html.TextBox("Latitude") %> <%= Html.ValidationMessage("Latitude", "*") %>

Longitude: <%= Html.TextBox("Longitude") %>

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

Page 71 of 186

<%= Html.ValidationMessage("Longitude", "*") %>

<% } %>

When we run the application and request the “/Dinners/Edit/1” URL we will see the following page:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

Page 72 of 186

The HTML markup generated by our view looks like below. It is standard HTML – with a
element that performs an HTTP POST to the /Dinners/Edit/1 URL when the “Save” button is pushed. A HTML element has been output for each editable property:

Html.BeginForm() and Html.TextBox() Html Helper Methods Our “Edit.aspx” view template is using several “Html Helper” methods: Html.ValidationSummary(), Html.BeginForm(), Html.TextBox(), and Html.ValidationMessage(). In addition to generating HTML markup for us, these helper methods provide built-in error handling and validation support. Html.BeginForm() helper method The Html.BeginForm() helper method is what output the HTML element in our markup. In our Edit.aspx view template you’ll notice that we are applying a C# “using” statement when using this method. The open curly brace indicates the beginning of the content, and the closing curly brace is what indicates the end of the
element: <% using (Html.BeginForm()) { %>
<% } %>

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

Page 73 of 186

Alternatively, if you find the “using” statement approach unnatural for a scenario like this, you can use a Html.BeginForm() and Html.EndForm() combination (which does the same thing): <% Html.BeginForm();

%>


<% Html.EndForm(); %>

Calling Html.BeginForm() without any parameters will cause it to output a form element that does an HTTP-POST to the current request’s URL. That is why our Edit view generates a
element. We could have alternatively passed explicit parameters to Html.BeginForm() if we wanted to post to a different URL. Html.TextBox() helper method Our Edit.aspx view uses the Html.TextBox() helper method to output elements: <%= Html.TextBox("Title") %>

The Html.TextBox() method above takes a single parameter – which is being used to specify both the id/name attributes of the element to output, as well as the model property to populate the textbox value from. For example, the Dinner object we passed to the Edit view had a “Title” property value of “.NET Futures”, and so our Html.TextBox(“Title”) method call output: . Alternatively, we can use the first Html.TextBox() parameter to specify the id/name of the element, and then explicitly pass in the value to use as a second parameter: <%= Html.TextBox("Title", Model.Title)%>

Often we’ll want to perform custom formatting on the value that is output. The String.Format() static method built-into .NET is useful for these scenarios. Our Edit.aspx view template is using this to format the EventDate value (which is of type DateTime) so that it doesn’t show seconds for the time: <%= Html.TextBox("EventDate", String.Format("{0:g}", Model.EventDate)) %>

A third parameter to Html.TextBox() can optionally be used to output additional HTML attributes. The code-snippet below demonstrates how to render an additional size=”30” attribute and a class=”mycssclass” attribute on the element. Note how we are escaping the name of the class attribute using a “@” character because “class” is a reserved keyword in C#: <%= Html.TextBox("Title", Model.Title, new { size=30, @class="myclass" } )%>

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

Page 74 of 186

Implementing the HTTP-POST Edit Action Method We now have the HTTP-GET version of our Edit action method implemented. When a user requests the /Dinners/Edit/1 URL they receive an HTML page like the following:

Pressing the “Save” button causes a form post to the /Dinners/Edit/1 URL, and submits the HTML form values using the HTTP POST verb. Let’s now implement the HTTP POST behavior of our edit action method – which will handle saving the Dinner. We’ll begin by adding an overloaded “Edit” action method to our DinnersController that has an “AcceptVerbs” attribute on it that indicates it handles HTTP POST scenarios:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

Page 75 of 186

// // POST: /Dinners/Edit/2 [AcceptVerbs(HttpVerbs.Post)] public ActionResult Edit(int id, FormCollection formValues) { ... }

When the [AcceptVerbs] attribute is applied to overloaded action methods, ASP.NET MVC automatically handles dispatching requests to the appropriate action method depending on the incoming HTTP verb. HTTP POST requests to /Dinners/Edit/[id] URLs will go to the above Edit method, while all other HTTP verb requests to /Dinners/Edit/[id] URLs will go to the first Edit method we implemented (which did not have an [AcceptVerbs] attribute). Side Topic: Why differentiate via HTTP verbs? You might ask – why are we using a single URL and differentiating its behavior via the HTTP verb? Why not just have two separate URLs to handle loading and saving edit changes? For example: /Dinners/Edit/[id] to display the initial form and /Dinners/Save/[id] to handle the form post to save it? The downside with publishing two separate URLs is that in cases where we post to /Dinners/Save/2, and then need to redisplay the HTML form because of an input error, the end-user will end up having the /Dinners/Save/2 URL in their browser’s address bar (since that was the URL the form posted to). If the end-user bookmarks this redisplayed page to their browser favorites list, or copy/pastes the URL and emails it to a friend, they will end up saving a URL that won’t work in the future (since that URL depends on post values). By exposing a single URL (like: /Dinners/Edit/[id]) and differentiating the processing of it by HTTP verb, it is safe for end-users to bookmark the edit page and/or send the URL to others. Retrieving Form Post Values There are a variety of ways we can access posted form parameters within our HTTP POST “Edit” method. One simple approach is to just use the Request property on the Controller base class to access the form collection and retrieve the posted values directly: // // POST: /Dinners/Edit/2 [AcceptVerbs(HttpVerbs.Post)] public ActionResult Edit(int id, FormCollection formValues) { // Retrieve existing dinner Dinner dinner = dinnerRepository.GetDinner(id); // Update dinner with form posted values dinner.Title = Request.Form["Title"]; dinner.Description = Request.Form["Description"]; dinner.EventDate = DateTime.Parse(Request.Form["EventDate"]); dinner.Address = Request.Form["Address"]; dinner.Country = Request.Form["Country"]; dinner.ContactPhone = Request.Form["ContactPhone"];

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

Page 76 of 186

// Persist changes back to database dinnerRepository.Save(); // Perform HTTP redirect to details page for the saved Dinner return RedirectToAction("Details", new { id = dinner.DinnerID }); }

The above approach is a little verbose, though, especially once we add error handling logic. A better approach for this scenario is to leverage the built-in UpdateModel() helper method on the Controller base class . It supports updating the properties of an object we pass it using the incoming form parameters. It uses reflection to determine the property names on the object, and then automatically converts and assigns values to them based on the input values submitted by the client. We could use the UpdateModel() method to implement our HTTP-POST Edit Action using this code: // // POST: /Dinners/Edit/2 [AcceptVerbs(HttpVerbs.Post)] public ActionResult Edit(int id, FormCollection formValues) { Dinner dinner = dinnerRepository.GetDinner(id); UpdateModel(dinner); dinnerRepository.Save(); return RedirectToAction("Details", new { id = dinner.DinnerID }); }

We can now visit the /Dinners/Edit/1 URL, and change the title of our Dinner:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

Page 77 of 186

When we click the “Save” button, we’ll perform a form post to our Edit action, and the updated values will be persisted in the database. We will then be redirected to the Details URL for the Dinner (which will display the newly saved values):

Handling Edit Errors Our current HTTP-POST implementation works fine – except when there are errors. When a user makes a mistake editing a form, we need to make sure that the form is redisplayed with an informative error message that guides them to fix it. This includes cases where an end-user posts incorrect input (for example: a malformed date string), as well as cases where the input format is valid but there is a business rule violation. When errors occur the form should preserve the input data the user originally entered so that they don’t have to refill their changes manually. This process should repeat as many times as necessary until the form successfully completes. ASP.NET MVC includes some nice built-in features that make error handling and form redisplay easy. To see these features in action let’s update our Edit action method with the following code:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

Page 78 of 186

// // POST: /Dinners/Edit/2 [AcceptVerbs(HttpVerbs.Post)] public ActionResult Edit(int id, FormCollection formValues) { Dinner dinner = dinnerRepository.GetDinner(id); try { UpdateModel(dinner); dinnerRepository.Save(); return RedirectToAction("Details", new { id=dinner.DinnerID }); } catch { foreach (var issue in dinner.GetRuleViolations()) { ModelState.AddModelError(issue.PropertyName, issue.ErrorMessage); } return View(dinner); } }

The above code is similar to our previous implementation – except that we are now wrapping a try/catch error handling block around our work. If an exception occurs either when calling UpdateModel(), or when we try and save the DinnerRepository (which will raise an exception if the Dinner object we are trying to save is invalid because of a rule violation), our catch error handling block will execute. Within it we loop over any rule violations that exist in the Dinner object and add them to a ModelState object (which we’ll discuss shortly). We then redisplay the view. To see this working let’s re-run the application, edit a Dinner, and change it to have an empty Title, an EventDate of “BOGUS”, and use a UK phone number with a country value of USA. When we press the “Save” button our HTTP POST Edit method will not be able to save the Dinner (because there are errors) and will redisplay the form:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

Page 79 of 186

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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Our application has a decent error experience. The text elements with the invalid input are highlighted in red, and validation error messages are displayed to the end user about them. The form is also preserving the input data the user originally entered – so that they don’t have to refill anything. How, you might ask, did this occur? How did the Title, EventDate, and ContactPhone textboxes highlight themselves in red and know to output the originally entered user values? And how did error messages get displayed in the list at the top? The good news is that this didn’t occur by magic - rather it was because we used some of the built-in ASP.NET MVC features that make input validation and error handling scenarios easy.

Understanding ModelState and the Validation HTML Helper Methods Controller classes have a “ModelState” property collection which provides a way to indicate that errors exist with a model object being passed to a View. Error entries within the ModelState collection identify the name of the model property with the issue (for example: “Title”, “EventDate”, or “ContactPhone”), and allow a human-friendly error message to be specified (for example: “Title is required”). The UpdateModel() helper method automatically populates the ModelState collection when it encounters errors while trying to assign form values to properties on the model object. For example, our Dinner object’s EventDate property is of type DateTime. When the UpdateModel() method was unable to assign the string value “BOGUS” to it in the scenario above, the UpdateModel() method added an entry to the ModelState collection indicating an assignment error had occurred with that property. Developers can also write code to explicitly add error entries into the ModelState collection like we are doing below within our “catch” error handling block, which is populating the ModelState collection with entries based on the active Rule Violations in the Dinner object: [AcceptVerbs(HttpVerbs.Post)] public ActionResult Edit(int id, FormCollection formValues) { Dinner dinner = dinnerRepository.GetDinner(id); try { UpdateModel(dinner); dinnerRepository.Save(); return RedirectToAction("Details", new { id=dinner.DinnerID }); } catch { foreach (var issue in dinner.GetRuleViolations()) { ModelState.AddModelError(issue.PropertyName, issue.ErrorMessage); } return View(dinner); } }

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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Html Helper Integration with ModelState HTML helper methods - like Html.TextBox() - check the ModelState collection when rendering output. If an error for the item exists, they render the user-entered value and a CSS error class. For example, in our "Edit" view we are using the Html.TextBox() helper method to render the EventDate of our Dinner object: <%= Html.TextBox("EventDate", String.Format("{0:g}", Model.EventDate)) %>

When the view was rendered in the error scenario, the Html.TextBox() method checked the ModelState collection to see if there were any errors associated with the "EventDate" property of our Dinner object. When it determined that there was an error it rendered the submitted user input ("BOGUS") as the value, and added a css error class to the markup it generated:

You can customize the appearance of the css error class to look however you want. The default CSS error class – “input-validation-error” – is defined in the \content\site.css stylesheet and looks like below: .input-validation-error { border: 1px solid #ff0000; background-color: #ffeeee; }

This CSS rule is what caused our invalid input elements to be highlighted like below:

Html .ValidationMessage() Helper Method The Html.ValidationMessage() helper method can be used to output the ModelState error message associated with a particular model property: <%= Html.ValidationMessage("EventDate") %>

The above code outputs: <span class=”field-validation-error”> The value ‘BOGUS’ is invalid The Html.ValidationMessage() helper method also supports a second parameter that allows developers to override the error text message that is displayed: <%= Html.ValidationMessage("EventDate", "*") %>

The above code outputs: <span class=”field-validation-error”>* instead of the default error text when an error is present for the EventDate property.

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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Html.ValidationSummary() Helper Method The Html.ValidationSummary() helper method can be used to render a summary error message, accompanied by a

list of all detailed error messages in the ModelState collection:

The Html.ValidationSummary() helper method takes an optional string parameter – which defines a summary error message to display above the list of detailed errors: <%= Html.ValidationSummary("Please correct the errors and try again.") %>

You can optionally use CSS to override what the error list looks like.

Using a AddRuleViolations Helper Method Our initial HTTP-POST Edit implementation used a foreach statement within its catch block to loop over the Dinner object’s Rule Violations and add them to the controller’s ModelState collection: catch { foreach (var issue in dinner.GetRuleViolations()) { ModelState.AddModelError(issue.PropertyName, issue.ErrorMessage); } return View(dinner); }

We can make this code a little cleaner by adding a “ControllerHelpers” class to the NerdDinner project, and implement an “AddRuleViolations” extension method within it that adds a helper method to the ASP.NET MVC ModelStateDictionary class. This extension method can encapsulate the logic necessary to populate the ModelStateDictionary with a list of RuleViolation errors:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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public static class ControllerHelpers { public static void AddRuleViolations(this ModelStateDictionary modelState, IEnumerable errors) { foreach (RuleViolation issue in errors) { modelState.AddModelError(issue.PropertyName, issue.ErrorMessage); } } }

We can then update our HTTP-POST Edit action method to use this extension method to populate the ModelState collection with our Dinner Rule Violations.

Complete Edit Action Method Implementations The code below implements all of the controller logic necessary for our Edit scenario: // // GET: /Dinners/Edit/2 public ActionResult Edit(int id) { Dinner dinner = dinnerRepository.GetDinner(id); return View(dinner); } // // POST: /Dinners/Edit/2 [AcceptVerbs(HttpVerbs.Post)] public ActionResult Edit(int id, FormCollection formValues) { Dinner dinner = dinnerRepository.GetDinner(id); try { UpdateModel(dinner); dinnerRepository.Save(); return RedirectToAction("Details", new { id=dinner.DinnerID }); } catch { ModelState.AddRuleViolations(dinner.GetRuleViolations()); return View(dinner); } }

The nice thing about our Edit implementation is that neither our Controller class nor our View template has to know anything about the specific validation or business rules being enforced by our Dinner model. We can add additional rules to our model in the future and do not have to make any code changes to our controller or view in order for them to be supported. This provides us with the flexibility to easily evolve our application requirements in the future with a minimum of code changes. Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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Implementing the HTTP-GET Create Action Method We’ve finished implementing the “Edit” behavior of our DinnersController class. Let’s now move on to implement the “Create” support on it – which will enable users to add new Dinners. We’ll begin by implementing the HTTP “GET” behavior of our create action method. This method will be called when someone visits the /Dinners/Create URL. Our implementation looks like: // // GET: /Dinners/Create public ActionResult Create() { Dinner dinner = new Dinner() { EventDate = DateTime.Now.AddDays(7) }; return View(dinner); }

The code above creates a new Dinner object, and assigns its EventDate property to be one week in the future. It then renders a View that is based on the new Dinner object. Because we haven’t explicitly passed a name to the View() helper method, it will use the convention based default path to resolve the view template: /Views/Dinners/Create.aspx. Let’s now create this view template. We can do this by right-clicking within the Create action method and selecting the “Add View” context menu command. Within the “Add View” dialog we’ll indicate that we are passing a Dinner object to the view template, and choose to auto-scaffold a “Create” template:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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When we click the “Add” button, Visual Studio will save a new scaffold-based “Create.aspx” view to the “\Views\Dinners” directory, and open it up within the IDE:

Let’s make a few changes to the default “create” scaffold file that was generated for us, and modify it up to look like below: Host a Dinner

Host a Dinner

<%= Html.ValidationSummary("Please correct the errors and try again.") %> <% using (Html.BeginForm()) {%>

Title: <%= Html.TextBox("Title") %> <%= Html.ValidationMessage("Title", "*") %>

Event Date: <%= Html.TextBox("EventDate") %>

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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<%= Html.ValidationMessage("EventDate", "*") %>

Description: <%= Html.TextArea("Description") %> <%= Html.ValidationMessage("Description", "*") %>

Address: <%= Html.TextBox("Address") %> <%= Html.ValidationMessage("Address", "*") %>

Country: <%= Html.TextBox("Country") %> <%= Html.ValidationMessage("Country", "*") %>

ContactPhone: <%= Html.TextBox("ContactPhone") %> <%= Html.ValidationMessage("ContactPhone", "*") %>

Latitude: <%= Html.TextBox("Latitude") %> <%= Html.ValidationMessage("Latitude", "*") %>

Longitude: <%= Html.TextBox("Longitude") %> <%= Html.ValidationMessage("Longitude", "*") %>

<% } %>

And now when we run our application and access the “/Dinners/Create” URL within the browser it will render UI like below from our Create action implementation:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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Implementing the HTTP-POST Create Action Method We have the HTTP-GET version of our Create action method implemented. When a user clicks the “Save” button it performs a form post to the /Dinners/Create URL, and submits the HTML form values using the HTTP POST verb. Let’s now implement the HTTP POST behavior of our create action method. We’ll begin by adding an overloaded “Create” action method to our DinnersController that has an “AcceptVerbs” attribute on it that indicates it handles HTTP POST scenarios:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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// // POST: /Dinners/Create [AcceptVerbs(HttpVerbs.Post)] public ActionResult Create() { ... }

There are a variety of ways we can access the posted form parameters within our HTTP-POST enabled “Create” method. One approach is to create a new Dinner object and then use the UpdateModel() helper method (like we did with the Edit action) to populate it with the posted form values. We can then add it to our DinnerRepository, persist it to the database, and redirect the user to our Details action to show the newly created Dinner using the code below: // // POST: /Dinners/Create [AcceptVerbs(HttpVerbs.Post)] public ActionResult Create() { Dinner dinner = new Dinner(); try { UpdateModel(dinner); dinnerRepository.Add(dinner); dinnerRepository.Save(); return RedirectToAction("Details", new {id=dinner.DinnerID}); } catch { ModelState.AddRuleViolations(dinner.GetRuleViolations()); return View(dinner); } }

Alternatively, we can use an approach where we have our Create() action method take a Dinner object as a method parameter. ASP.NET MVC will then automatically instantiate a new Dinner object for us, populate its properties using the form inputs, and pass it to our action method:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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// // POST: /Dinners/Create [AcceptVerbs(HttpVerbs.Post)] public ActionResult Create(Dinner dinner) { if (ModelState.IsValid) { try { dinner.HostedBy = "SomeUser"; dinnerRepository.Add(dinner); dinnerRepository.Save(); return RedirectToAction("Details", new {id = dinner.DinnerID }); } catch { ModelState.AddRuleViolations(dinner.GetRuleViolations()); } } return View(dinner); }

Our action method above verifies that the Dinner object has been successfully populated with the form post values by checking the ModelState.IsValid property. This will return false if there are input conversion issues (for example: a string of “BOGUS” for the EventDate property), and if there are any issues our action method redisplays the form. If the input values are valid, then the action method attempts to add and save the new Dinner to the DinnerRepository. It wraps this work within a try/catch block and redisplays the form if there are any business rule violations (which would cause the dinnerRepository.Save() method to raise an exception). To see this error handling behavior in action, we can request the /Dinners/Create URL and fill out details about a new Dinner. Incorrect input or values will cause the create form to be redisplayed with the errors highlighted like below:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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Notice how our Create form is honoring the exact same validation and business rules as our Edit form. This is because our validation and business rules were defined in the model, and were not embedded within the UI or controller of the application. This means we can later change/evolve our validation or business rules in a single place and have them apply throughout our application. We will not have to change any code within either our Edit or Create action methods to automatically honor any new rules or modifications to existing ones. When we fix the input values and click the “Save” button again, our addition to the DinnerRepository will succeed, and a new Dinner will be added to the database. We will then be redirected to the /Dinners/Details/[id] URL – where we will be presented with details about the newly created Dinner:

Implementing the HTTP-GET Delete Action Method Let’s now add “Delete” support to our DinnersController. We’ll begin by implementing the HTTP GET behavior of our delete action method. This method will get called when someone visits the /Dinners/Delete/[id] URL . Below is the implementation:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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// // HTTP GET: /Dinners/Delete/1 public ActionResult Delete(int id) { Dinner dinner = dinnerRepository.GetDinner(id); if (dinner == null) return View("NotFound"); else return View(dinner); }

The action method attempts to retrieve the Dinner to be deleted. If the Dinner exists it renders a View based on the Dinner object. If the object doesn’t exist (or has already been deleted) it returns a View that renders the “NotFound” view template we created earlier for our “Details” action method. We can create the “Delete” view template by right-clicking within the Delete action method and selecting the “Add View” context menu command. Within the “Add View” dialog we’ll indicate that we are passing a Dinner object to our view template as its model, and choose to create an empty template:

When we click the “Add” button, Visual Studio will add a new “Delete.aspx” view template file for us within our “\Views\Dinners” directory. We’ll add some HTML and code to the template to implement a delete confirmation screen like below:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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Delete Confirmation: <%=Html.Encode(Model.Title) %>

Delete Confirmation

Please confirm you want to cancel the dinner titled: <%=Html.Encode(Model.Title) %>?

<% using (Html.BeginForm()) { %> <% } %>

The code above displays the title of the Dinner to be deleted, and outputs a element that does a POST to the /Dinners/Delete/[id] URL if the end-user clicks the “Delete” button within it. When we run our application and access the “/Dinners/Delete/[id]” URL for a valid Dinner object it renders UI like below:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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Side Topic: Why are we doing a POST? You might ask – why did we go through the effort of creating a within our Delete confirmation screen? Why not just use a standard hyperlink to link to an action method that does the actual delete operation? The reason is because we want to be careful to guard against web-crawlers and search engines discovering our URLs and inadvertently causing data to be deleted when they follow the links. HTTPGET based URLs are considered “safe” for them to access/crawl, and they are supposed to not follow HTTP-POST ones. A good rule is to make sure you always put destructive or data modifying operations behind HTTP-POST requests.

Implementing the HTTP-POST Delete Action Method We now have the HTTP-GET version of our Delete action method implemented which displays a delete confirmation screen. When an end user clicks the “Delete” button it will perform a form post to the /Dinners/Dinner/[id] URL. Let’s now implement the HTTP “POST” behavior of the delete action method using the code below: // // HTTP POST: /Dinners/Delete/1 [AcceptVerbs(HttpVerbs.Post)] public ActionResult Delete(int id, string confirmButton) { Dinner dinner = dinnerRepository.GetDinner(id); if (dinner == null) return View("NotFound"); dinnerRepository.Delete(dinner); dinnerRepository.Save(); return View("Deleted"); }

The HTTP-POST version of our Delete action method attempts to retrieve the dinner object to delete. If it can’t find it (because it has already been deleted) it renders our “NotFound” template. If it finds the Dinner, it deletes it from the DinnerRepository. It then renders a “Deleted” template. To implement the “Deleted” template we’ll right-click in the action method and choose the “Add View” context menu. We’ll name our view “Deleted” and have it be an empty template (and not take a strongly-typed model object). We’ll then add some HTML content to it: Dinner Deleted

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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Dinner Deleted

Your dinner was successfully deleted.

Click for Upcoming Dinners



And now when we run our application and access the “/Dinners/Delete/[id]” URL for a valid Dinner object it will render our Dinner delete confirmation screen like below:

When we click the “Delete” button it will perform an HTTP-POST to the /Dinners/Delete/[id] URL, which will delete the Dinner from our database, and display our “Deleted” view template:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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Model Binding Security We’ve discussed two different ways to use the built-in model-binding features of ASP.NET MVC. The first using the UpdateModel() method to update properties on an existing model object, and the second using ASP.NET MVC’s support for passing model objects in as action method parameters. Both of these techniques are very powerful and extremely useful. This power also brings with it responsibility. It is important to always be paranoid about security when accepting any user input, and this is also true when binding objects to form input. You should be careful to always HTML encode any user-entered values to avoid HTML and JavaScript injection attacks, and be careful of SQL injection attacks (note: we are using LINQ to SQL for our application, which automatically encodes parameters to prevent these types of attacks). You should never rely on client-side validation alone, and always employ server-side validation to guard against hackers attempting to send you bogus values. One additional security item to make sure you think about when using the binding features of ASP.NET MVC is the scope of the objects you are binding. Specifically, you want to make sure you understand the security implications of the properties you are allowing to be bound, and make sure you only allow those properties that really should be updatable by an end-user to be updated. By default, the UpdateModel() method will attempt to update all properties on the model object that match incoming form parameter values. Likewise, objects passed as action method parameters also by default can have all of their properties set via form parameters. Locking down binding on a per-usage basis You can lock down the binding policy on a per-usage basis by providing an explicit “include list” of properties that can be updated. This can be done by passing an extra string array parameter to the UpdateModel() method like below: string[] allowedProperties = new[]{ "Title", "Description", "ContactPhone", "Address", "EventDate", "Latitude", "Longitude"}; UpdateModel(dinner, allowedProperties);

Objects passed as action method parameters also support a [Bind] attribute that enables an “include list” of allowed properties to be specified like below: // // POST: /Dinners/Create [AcceptVerbs(HttpVerbs.Post)] public ActionResult Create( [Bind(Include="Title,Address")] Dinner dinner ) { ... }

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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Locking down binding on a type basis You can also lock down the binding rules on a per-type basis. This allows you to specify the binding rules once, and then have them apply in all scenarios (including both UpdateModel and action method parameter scenarios) across all controllers and action methods. You can customize the per-type binding rules by adding a [Bind] attribute onto a type, or by registering it within the Global.asax file of the application (useful for scenarios where you don’t own the type). You can then use the Bind attribute’s Include and Exclude properties to control which properties are bindable for the particular class or interface. We’ll use this technique for the Dinner class in our NerdDinner application, and add a [Bind] attribute to it that restricts the list of bindable properties to the following: [Bind(Include="Title,Description,EventDate,Address,Country,ContactPhone,Latitude,Longi tude")] public partial class Dinner { }

Notice we are not allowing the RSVPs collection to be manipulated via binding, nor are we allowing the DinnerID or HostedBy properties to be set via binding. For security reasons we’ll instead only manipulate these particular properties using explicit code within our action methods.

CRUD Wrap-Up ASP.NET MVC includes a number of built-in features that help with implementing form posting scenarios. We used a variety of these features to provide CRUD UI support on top of our DinnerRepository. We are using a model-focused approach to implement our application. This means that all our validation and business rule logic is defined within our model layer – and not within our controllers or views. Neither our Controller class nor our View templates know anything about the specific business rules being enforced by our Dinner model class. This will keep our application architecture clean and make it easier to test. We can add additional business rules to our model layer in the future and not have to make any code changes to our Controller or View in order for them to be supported. This is going to provide us with a great deal of agility to evolve and change our application in the future. Our DinnersController now enables Dinner listings/details, as well as create, edit and delete support. The complete code for the class can be found below:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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public class DinnersController : Controller { DinnerRepository dinnerRepository = new DinnerRepository(); // // GET: /Dinners/ public ActionResult Index() { var dinners = dinnerRepository.FindUpcomingDinners().ToList(); return View(dinners); } // // GET: /Dinners/Details/2 public ActionResult Details(int id) { Dinner dinner = dinnerRepository.GetDinner(id); if (dinner == null) return View("NotFound"); else return View(dinner); } // // GET: /Dinners/Edit/2 public ActionResult Edit(int id) { Dinner dinner = dinnerRepository.GetDinner(id); return View(dinner); } // // POST: /Dinners/Edit/2 [AcceptVerbs(HttpVerbs.Post)] public ActionResult Edit(int id, FormCollection formValues) { Dinner dinner = dinnerRepository.GetDinner(id); try { UpdateModel(dinner); dinnerRepository.Save(); return RedirectToAction("Details", new { id = dinner.DinnerID }); } catch { ModelState.AddRuleViolations(dinner.GetRuleViolations()); return View(dinner); } }

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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// // GET: /Dinners/Create public ActionResult Create() { Dinner dinner = new Dinner() { EventDate = DateTime.Now.AddDays(7) }; return View(dinner); } // // POST: /Dinners/Create [AcceptVerbs(HttpVerbs.Post)] public ActionResult Create(Dinner dinner) { if (ModelState.IsValid) { try { dinner.HostedBy = "SomeUser"; dinnerRepository.Add(dinner); dinnerRepository.Save(); return RedirectToAction("Details", new{id=dinner.DinnerID}); } catch { ModelState.AddRuleViolations(dinner.GetRuleViolations()); } } return View(dinner); } // // HTTP GET: /Dinners/Delete/1 public ActionResult Delete(int id) { Dinner dinner = dinnerRepository.GetDinner(id); if (dinner == null) return View("NotFound"); else return View(dinner); }

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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// // HTTP POST: /Dinners/Delete/1 [AcceptVerbs(HttpVerbs.Post)] public ActionResult Delete(int id, string confirmButton) { Dinner dinner = dinnerRepository.GetDinner(id); if (dinner == null) return View("NotFound"); dinnerRepository.Delete(dinner); dinnerRepository.Save(); return View("Deleted"); } }

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

Page 101 of 186

ViewData and ViewModel

We’ve covered a number of form post scenarios, and discussed how to implement create, update and delete (CRUD) support. We’ll now take our DinnersController implementation further and enable support for richer form editing scenarios. While doing this we’ll discuss two approaches that can be used to pass data from controllers to views: ViewData and ViewModel.

Passing Data from Controllers to View-Templates One of the defining characteristics of the MVC pattern is the strict “separation of concerns” it helps enforce between the different components of an application. Models, Controllers and Views each have well defined roles and responsibilities, and they communicate amongst each other in well defined ways. This helps promote testability and code reuse. When a Controller class decides to render an HTML response back to a client, it is responsible for explicitly passing to the view template all of the data needed to render the response. View templates should never perform any data retrieval or application logic – and should instead limit themselves to only have rendering code that is driven off of the model/data passed to it by the controller. Right now the model data being passed by our DinnersController class to our view templates is simple and straight-forward – a list of Dinner objects in the case of Index(), and a single Dinner object in the case of Details(), Edit(), Create() and Delete(). As we add more UI capabilities to our application, we are often going to need to pass more than just this data to render HTML responses within our view templates. For example, we might want to change the “Country” field within our Edit and Create views from being an HTML textbox to a dropdownlist. Rather than hard-code the dropdown list of country names in the view template, we might want to generate it from a list of supported countries that we populate dynamically. We will need a way to pass both the Dinner object and the list of supported countries from our controller to our view templates. Let’s look at two ways we can accomplish this.

Using the ViewData Dictionary The Controller base class exposes a “ViewData” dictionary property that can be used to pass additional data items from Controllers to Views. For example, to support the scenario where we want to change the “Country” textbox within our Edit view from being an HTML textbox to a dropdownlist, we can update our Edit() action method to pass (in addition to a Dinner object) a SelectList object that can be used as the model of a countries dropdownlist.

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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// // GET: /Dinners/Edit/5 [Authorize] public ActionResult Edit(int id) { Dinner dinner = dinnerRepository.GetDinner(id); ViewData["Countries"] = new SelectList(PhoneValidator.Countries, dinner.Country); return View(dinner); }

The constructor of the SelectList above is accepting a list of countries to populate the drop-downlist with, as well as the currently selected value. We can then update our Edit.aspx view template to use the Html.DropDownList() helper method instead of the Html.TextBox() helper method we used previously: <%= Html.DropDownList("Country", ViewData["Countries"] as SelectList) %>

The Html.DropDownList() helper method above takes two parameters. The first is the name of the HTML form element to output. The second is the “SelectList” model we passed via the ViewData dictionary. We are using the C# “as” keyword to cast the type within the dictionary as a SelectList. And now when we run our application and access the /Dinners/Edit/1 URL within our browser we’ll see that our edit UI has been updated to display a dropdownlist of countries instead of a textbox:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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Because we also render the Edit view template from the HTTP-POST Edit method (in scenarios when errors occur), we’ll want to make sure that we also update this method to add the SelectList to ViewData when the view template is rendered in error scenarios: // // POST: /Dinners/Edit/5 [AcceptVerbs(HttpVerbs.Post)] public ActionResult Edit(int id, FormCollection collection) { Dinner dinner = dinnerRepository.GetDinner(id); try { UpdateModel(dinner); dinnerRepository.Save(); return RedirectToAction("Details", new { id=dinner.DinnerID }); } catch { ModelState.AddModelErrors(dinner.GetRuleViolations()); ViewData["countries"] = new SelectList(PhoneValidator.Countries, dinner.Country); return View(dinner); } }

And now our DinnersController edit scenario supports a DropDownList.

Using a ViewModel Pattern The ViewData dictionary approach has the benefit of being fairly fast and easy to implement. Some developers don’t like using string-based dictionaries, though, since typos can lead to errors that will not be caught at compile-time. The un-typed ViewData dictionary also requires using the “as” operator or casting when using a strongly-typed language like C# in a view template. An alternative approach that we could use is one often referred to as the “ViewModel” pattern. When using this pattern we create strongly-typed classes that are optimized for our specific view scenarios, and which expose properties for the dynamic values/content needed by our view templates. Our controller classes can then populate and pass these view-optimized classes to our view template to use. This enables type-safety, compile-time checking, and editor intellisense within view templates. For example, to enable dinner form editing scenarios we can create a “DinnerFormViewModel” class like below that exposes two strongly-typed properties: a Dinner object, and the SelectList model needed to populate the countries dropdownlist:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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public class DinnerFormViewModel { // Properties public Dinner Dinner { get; private set; } public SelectList Countries { get; private set; } // Constructor public DinnerFormViewModel(Dinner dinner) { Dinner = dinner; Countries = new SelectList(PhoneValidator.Countries, dinner.Country); } }

We can then update our Edit() action method to create the DinnerFormViewModel using the Dinner object we retrieve from our repository, and then pass it to our view template: // // GET: /Dinners/Edit/5 [Authorize] public ActionResult Edit(int id) { Dinner dinner = dinnerRepository.GetDinner(id); return View(new DinnerFormViewModel(dinner)); }

We’ll then update our view template so that it expects a “DinnerFormViewModel” instead of a “Dinner” object by changing the “inherits” attribute at the top of the edit.aspx page like so: Inherits="System.Web.Mvc.ViewPage

Once we do this, the intellisense of the “Model” property within our view template will be updated to reflect the object model of the DinnerFormViewModel type we are passing it:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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We can then update our view code to work off of it. Notice below how we are not changing the names of the input elements we are creating (the form elements will still be named “Title”, “Country”) – but we are updating the HTML Helper methods to retrieve the values using the DinnerFormViewModel class:

Dinner Title: <%= Html.TextBox("Title", Model.Dinner.Title) %> <%= Html.ValidationMessage("Title", "*") %>

Country: <%= Html.DropDownList("Country", Model.Countries) %> <%= Html.ValidationMessage("Country", "*") %>



We’ll also update our Edit post method to use the DinnerFormViewModel class when rendering errors: // // POST: /Dinners/Edit/5 [AcceptVerbs(HttpVerbs.Post)] public ActionResult Edit(int id, FormCollection collection) { Dinner dinner = dinnerRepository.GetDinner(id); try { UpdateModel(dinner); dinnerRepository.Save(); return RedirectToAction("Details", new { id=dinner.DinnerID }); } catch { ModelState.AddModelErrors(dinner.GetRuleViolations()); return View(new DinnerFormViewModel(dinner)); } }

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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We can also update our Create() action methods to re-use the exact same DinnerFormViewModel class to enable the countries DropDownList within those as well. Below is the HTTP-GET implementation: // // GET: /Dinners/Create public ActionResult Create() { Dinner dinner = new Dinner() { EventDate = DateTime.Now.AddDays(7) }; return View(new DinnerFormViewModel(dinner)); }

Below is the implementation of the HTTP-POST Create method: // // POST: /Dinners/Create [AcceptVerbs(HttpVerbs.Post)] public ActionResult Create(Dinner dinner) { if (ModelState.IsValid) { try { dinner.HostedBy = "SomeUser"; dinnerRepository.Add(dinner); dinnerRepository.Save(); return RedirectToAction("Details", new { id=dinner.DinnerID }); } catch { ModelState.AddModelErrors(dinnerToCreate.GetRuleViolations()); } } return View(new DinnerFormViewModel(dinnerToCreate)); }

And now both our Edit and Create screens support drop-downlists for picking the country.

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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Custom-shaped ViewModel classes In the scenario above, our DinnerFormViewModel class directly exposes the Dinner model object as a property, along with a supporting SelectList model property. This approach works fine for scenarios where the HTML UI we want to create within our view template corresponds relatively closely to our domain model objects. For scenarios where this isn’t the case, one option that you can use is to create a custom-shaped ViewModel class whose object model is more optimized for consumption by the view – and which might look completely different from the underlying domain model object. For example, it could potentially expose different property names and/or aggregate properties collected from multiple model objects. Custom-shaped ViewModel classes can be used both to pass data from controllers to views to render, as well as to help handle form data posted back to a controller’s action method. For this later scenario, you might have the action method update a ViewModel object with the form-posted data, and then use the ViewModel instance to map or retrieve an actual domain model object. Custom-shaped ViewModel classes can provide a great deal of flexibility, and are something to investigate any time you find the rendering code within your view templates or the form-posting code inside your action methods starting to get too complicated. This is often a sign that your domain models don’t cleanly correspond to the UI you are generating, and that an intermediate custom-shaped ViewModel class can help.

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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Partials and Master Pages

One of the design philosophies ASP.NET MVC embraces is the “Do Not Repeat Yourself” principle (commonly referred to as “DRY”). A DRY design helps eliminate the duplication of code and logic, which ultimately makes applications faster to build and easier to maintain. We’ve already seen the DRY principle applied in several of our NerdDinner scenarios. A few examples: our validation logic is implemented within our model layer, which enables it to be enforced across both edit and create scenarios in our controller; we are re-using the “NotFound” view template across the Edit, Details and Delete action methods; we are using a convention- naming pattern with our view templates, which eliminates the need to explicitly specify the name when we call the View() helper method; and we are re-using the DinnerFormViewModel class for both Edit and Create action scenarios. Let’s now look at ways we can apply the “DRY Principle” within our view templates to eliminate code duplication there as well.

Re-visiting our Edit and Create View Templates Currently we are using two different view templates – “Edit.aspx” and “Create.aspx” – to display our Dinner form UI. A quick visual comparison of them highlights how similar they are. Below is what the create form looks like:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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And here is what our “Edit” form looks like:

Not much of a difference is there? Other than the title and header text, the form layout and input controls are identical. If we open up the “Edit.aspx” and “Create.aspx” view templates we’ll find that they contain identical form layout and input control code. This duplication means we end up having to make changes twice anytime we introduce or change a new Dinner property - which is not good.

Using Partial View Templates ASP.NET MVC supports the ability to define “partial view” templates that can be used to encapsulate view rendering logic for a sub-portion of a page. “Partials” provide a useful way to define view rendering logic once, and then re-use it in multiple places across an application. To help “DRY-up” our Edit.aspx and Create.aspx view template duplication, we can create a partial view template named “DinnerForm.ascx” that encapsulates the form layout and input elements common to both. We’ll do this by right-clicking on our /Views/Dinners directory and choosing the “Add->View” menu command:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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This will display the “Add View” dialog. We’ll name the new view we want to create “DinnerForm”, select the “Create a partial view” checkbox within the dialog, and indicate that we will pass it a DinnerFormViewModel class:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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When we click the “Add” button, Visual Studio will create a new “DinnerForm.ascx” view template for us within the “\Views\Dinners” directory. We can then copy/paste the duplicate form layout / input control code from our Edit.aspx/ Create.aspx view templates into our new “DinnerForm.ascx” partial view template: <%= Html.ValidationSummary("Please correct the errors and try again.") %> <% using (Html.BeginForm()) { %>

Dinner Title: <%= Html.TextBox("Title", Model.Dinner.Title) %> <%= Html.ValidationMessage("Title", "*") %>

Event Date: <%= Html.TextBox("EventDate", Model.Dinner.EventDate) %> <%= Html.ValidationMessage("EventDate", "*") %>

Description: <%= Html.TextArea("Description", Model.Dinner.Description) %> <%= Html.ValidationMessage("Description", "*")%>

Address: <%= Html.TextBox("Address", Model.Dinner.Address) %> <%= Html.ValidationMessage("Address", "*") %>

Country: <%= Html.DropDownList("Country", Model.Countries) %> <%= Html.ValidationMessage("Country", "*") %>

Contact Phone #: <%= Html.TextBox("ContactPhone", Model.Dinner.ContactPhone) %> <%= Html.ValidationMessage("ContactPhone", "*") %>

<% } %>

We can then update our Edit and Create view templates to call the DinnerForm partial template and eliminate the form duplication. We can do this by calling Html.RenderPartial(“DinnerForm”) within our view templates:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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Create.aspx Host a Dinner

Host a Dinner

<% Html.RenderPartial("DinnerForm"); %>

Edit.aspx Edit: <%=Html.Encode(Model.Dinner.Title) %>

Edit Dinner

<% Html.RenderPartial("DinnerForm"); %>

You can explicitly qualify the path of the partial template you want when calling Html.RenderPartial (for example: ~/Views/Dinners/DinnerForm.ascx"). In our code above, though, we are taking advantage of the convention-based naming pattern within ASP.NET MVC, and just specifying “DinnerForm” as the name of the partial to render. When we do this ASP.NET MVC will look first in the convention-based views directory (for DinnersController this would be /Views/Dinners). If it doesn’t find the partial template there it will then look for it in the /Views/Shared directory. When Html.RenderPartial() is called with just the name of the partial view, ASP.NET MVC will pass to the partial view the same Model and ViewData dictionary objects used by the calling view template. Alternatively, there are overloaded versions of Html.RenderPartial() that enable you to pass an alternate Model object and/or ViewData dictionary for the partial view to use. This is useful for scenarios where you only want to pass a subset of the full Model/ViewModel. Side Topic: Why <% %> instead of <%= %>? One of the subtle things you might have noticed with the code above is that we are using a <% %> block instead of a <%= %> block when calling Html.RenderPartial(). <%= %> blocks in ASP.NET indicate that a developer wants to render a specified value (for example: <%= “Hello” %> would render “Hello”). <% %> blocks instead indicate that the developer wants to execute code, and that any rendered output within them must be done explicitly (for example: <% Response.Write(“Hello”); %>.

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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The reason we are using a <% %> block with our Html.RenderPartial code above is because the Html.RenderPartial() method doesn’t return a string, and instead outputs the content directly to the calling view template’s output stream. It does this for performance efficiency reasons, and by doing so it avoids the need to create a (potentially very large) temporary string object. This reduces memory usage and improves overall application throughput. One common mistake when using Html.RenderPartial() is to forget to add a semi-colon at the end of the call when it is within a <% %> block. For example, this code will cause a compiler error: <% Html.RenderPartial(“DinnerForm”) %> You instead need to write: <% Html.RenderPartial(“DinnerForm”); %> This is because <% %> blocks are self-contained code statements, and when using C# code statements need to be terminated with a semi-colon.

Using Partial View Templates to Clarify Code We created the “DinnerForm” partial view template to avoid duplicating view rendering logic in multiple places. This is the most common reason to create partial view templates. Sometimes it still makes sense to create partial views even when they are only being called in a single place. Very complicated view templates can often become much easier to read when their view rendering logic is extracted and partitioned into one or more well named partial templates. For example, consider the below code-snippet from the Site.master file in our project (which we will be looking at shortly). The code is relatively straight-forward to read – partly because the logic to display a login/logout link at the top right of the screen is encapsulated within the “LogOnUserControl” partial:

My MVC Application

<% Html.RenderPartial("LogOnUserControl"); %>

• <%= Html.ActionLink("Home", "Index", "Home")%>
• <%= Html.ActionLink("About", "About", "Home")%>



Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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Whenever you find yourself getting confused trying to understand the html/code markup within a viewtemplate, consider whether it wouldn’t be clearer if some of it was extracted and refactored into wellnamed partial views.

Master Pages In addition to supporting partial views, ASP.NET MVC also supports the ability to create “master page” templates that can be used to define the common layout and top-level html of a site. Content placeholder controls can then be added to the master page to identify replaceable regions that can be overridden or “filled in” by views. This provides a very effective (and DRY) way to apply a common layout across an application. By default, new ASP.NET MVC projects have a master page template automatically added to them. This master page is named “Site.master” and lives within the \Views\Shared\ folder:

The default Site.master file looks like below. It defines the outer html of the site, along with a menu for navigation at the top. It contains two replaceable content placeholder controls – one for the title, and the other for where the primary content of a page should be replaced:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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<%@ Master Language="C#" Inherits="System.Web.Mvc.ViewMasterPage" %>

My MVC Application

<% Html.RenderPartial("LogOnUserControl"); %>

• <%= Html.ActionLink("Home", "Index", "Home")%>
• <%= Html.ActionLink("About", "About", "Home")%>



All of the view templates we’ve created for our NerdDinner application (“List”, “Details”, “Edit”, “Create”, “NotFound”, etc) have been based on this Site.master template. This is indicated via the “MasterPageFile” attribute that was added by default to the top <% @ Page %> directive when we created our views using the “Add View” dialog: <%@ Page Language="C#" Inherits="System.Web.Mvc.ViewPage" MasterPageFile="~/Views/Shared/Site.Master" %>

What this means is that we can change the Site.master content, and have the changes automatically be applied and used when we render any of our view templates. Let’s update our Site.master’s header section so that the header of our application is “NerdDinner” instead of “My MVC Application”. Let’s also update our navigation menu so that the first tab is “Find a

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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Dinner” (handled by the HomeController’s Index() action method), and let’s add a new tab called “Host a Dinner” (handled by the DinnersController’s Create() action method):

NerdDinner

<% Html.RenderPartial("LogOnUserControl"); %>

• <%= Html.ActionLink("Find Dinner", "Index", "Home")%>
• <%= Html.ActionLink("Host Dinner", "Create", "Dinners")%>
• <%= Html.ActionLink("About", "About", "Home")%>



When we save the Site.master file and refresh our browser we’ll see our header changes show up across all views within our application. For example:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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And with the /Dinners/Edit/[id] URL:

Partials and master pages provide very flexible options that enable you to cleanly organize views. You’ll find that they help you avoid duplicating view content/ code, and make your view templates easier to read and maintain.

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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Paging Support

If our site is successful, it will have thousands of upcoming dinners. We need to make sure that our UI scales to handle all of these dinners, and allows users to browse them. To enable this, we’ll add paging support to our /Dinners URL so that instead of displaying 1000s of dinners at once, we’ll only display 10 upcoming dinners at a time - and allow end-users to page back and forward through the entire list in an SEO friendly way.

Index() Action Method Recap The Index() action method within our DinnersController class currently looks like below: // // GET: /Dinners/ public ActionResult Index() { var dinners = dinnerRepository.FindUpcomingDinners().ToList(); return View(dinners); }

When a request is made to the /Dinners URL, it retrieves a list of all upcoming dinners and then renders a listing of all of them out:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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Understanding IQueryable IQueryable is an interface that was introduced with LINQ in .NET 3.5. It enables powerful “deferred execution” scenarios that we can take advantage of to implement paging support. In our DinnerRepository below we are returning an IQueryable sequence from our FindUpcomingDinners() method: public class DinnerRepository { private NerdDinnerDataContext db = new NerdDinnerDataContext(); // // Query Methods public IQueryable FindUpcomingDinners() { return from dinner in db.Dinners where dinner.EventDate > DateTime.Now orderby dinner.EventDate select dinner; }

The IQueryable object returned by our FindUpcomingDinners() method encapsulates a query to retrieve Dinner objects from our database using LINQ to SQL. Importantly, it won’t execute the query against the database until we attempt to access/iterate over the data in the query, or until we call the ToList()method on it. The code calling our FindUpcomingDinners() method can optionally choose to add additional “chained” operations/filters to the IQueryable object before executing the query. LINQ to SQL is then smart enough to execute the combined query against the database when the data is requested. To implement paging logic we can update our Index() action method so that it applies additional “Skip” and “Take” operators to the returned IQueryable sequence before calling ToList() on it: // // GET: /Dinners/ public ActionResult Index() { var upcomingDinners = dinnerRepository.FindUpcomingDinners(); var paginatedDinners = upcomingDinners.Skip(10).Take(20).ToList(); return View(paginatedDinners); }

The above code skips over the first 10 upcoming dinners in the database, and then returns back 20 dinners. LINQ to SQL is smart enough to construct an optimized SQL query that performs this skipping logic in the SQL database – and not in the web-server. This means that even if we have millions of upcoming Dinners in the database, only the 10 we want will be retrieved as part of this request (making it efficient and scalable).

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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Adding a “page” value to the URL Instead of hard-coding a specific page range, we’ll want our URLs to include a “page” parameter that indicates which Dinner range a user is requesting. Using a Querystring value The code below demonstrates how we can update our Index() action method to support a querystring parameter and enable URLs like /Dinners?page=2: // // GET: /Dinners/ // /Dinners?page=2 public ActionResult Index(int? page) { const int pageSize = 10; var upcomingDinners = dinnerRepository.FindUpcomingDinners(); var paginatedDinners = upcomingDinners.Skip((page ?? 0) * pageSize) .Take(pageSize) .ToList(); return View(paginatedDinners); }

The Index() action method above has a parameter named “page”. The parameter is declared as a nullable integer. This means that the /Dinners?page=2 URL will cause a value of “2” to be passed as the parameter value. The /Dinners URL (without a querystring value) will cause a null value to be passed. We are multiplying the page value by the page size (in this case 10 rows) to determine how many dinners to skip over. We are using the C# “coalescing” operator (??) which is useful when dealing with nullable types. The code above assigns page the value of 0 if the page parameter is null. Using Embedded URL values An alternative to using a querystring value would be to embed the page parameter within the actual URL itself. For example: /Dinners/Page/2 or /Dinners/2. ASP.NET MVC includes a powerful URL routing engine that makes it easy to support scenarios like this. We can register custom routing rules that map any incoming URL or URL format to any controller class or action method we want. All we need to-do is to open the Global.asax file within our project:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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And then register a new mapping rule using the MapRoute() helper method like the first call to routes.MapRoute() below: public void RegisterRoutes(RouteCollection routes) { routes.IgnoreRoute("{resource}.axd/{*pathInfo}"); routes.MapRoute( "UpcomingDinners", "Dinners/Page/{page}", new { controller = "Dinners", action = "Index" } ); routes.MapRoute( "Default", "{controller}/{action}/{id}", new { controller="Home", action="Index", id="" } );

// Route name // URL with params // Param defaults

} void Application_Start() { RegisterRoutes(RouteTable.Routes); }

Above we are registering a new routing rule named “UpcomingDinners”. We are indicating it has the URL format “Dinners/Page/{page}” – where {page} is a parameter value embedded within the URL. The third parameter to the MapRoute() method indicates that we should map URLs that match this format to the Index() action method on the DinnersController class.

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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We can use the exact same Index() code we had before with our Querystring scenario – except now our “page” parameter will come from the URL and not the querystring: // // GET: /Dinners/ // /Dinners/Page/2 public ActionResult Index(int? page) { const int pageSize = 10; var upcomingDinners = dinnerRepository.FindUpcomingDinners(); var paginatedDinners = upcomingDinners.Skip((page ?? 0) * pageSize) .Take(pageSize) .ToList(); return View(paginatedDinners); }

And now when we run the application and type in /Dinners we’ll see the first 10 upcoming dinners:

And when we type in /Dinners/Page/1 we’ll see the next page of dinners: Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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Adding page navigation UI The last step to complete our paging scenario will be to implement “next” and “previous” navigation UI within our view template to enable users to easily skip over the Dinner data. To implement this correctly, we’ll need to know the total number of Dinners in the database, as well as how many pages of data this translates to. We’ll then need to calculate whether the currently requested “page” value is at the beginning or end of the data, and show or hide the “previous” and “next” UI accordingly. We could implement this logic within our Index() action method. Alternatively we can add a helper class to our project that encapsulates this logic in a more re-usable way. Below is a simple “PaginatedList” helper class that derives from the List collection class built-into the .NET Framework. It implements a re-usable collection class that can be used to paginate any sequence of IQueryable data. In our NerdDinner application we’ll have it work over IQueryable results, but it could just as easily be used against IQueryable or IQueryable results in other application scenarios: public class PaginatedList : List { public public public public

int int int int

PageIndex PageSize TotalCount TotalPages

{ { { {

get; get; get; get;

private private private private

set; set; set; set;

} } } }

public PaginatedList(IQueryable source, int pageIndex, int pageSize) { PageIndex = pageIndex; PageSize = pageSize; TotalCount = source.Count();

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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TotalPages = (int) Math.Ceiling(TotalCount / (double)PageSize); this.AddRange(source.Skip(PageIndex * PageSize).Take(PageSize)); } public bool HasPreviousPage { get { return (PageIndex > 0); } } public bool HasNextPage { get { return (PageIndex+1 < TotalPages); } } }

Notice above how it calculates and then exposes properties like “PageIndex”, “PageSize”, “TotalCount”, and “TotalPages”. It also then exposes two helper properties “HasPreviousPage” and “HasNextPage” that indicate whether the page of data in the collection is at the beginning or end of the original sequence. The above code will cause two SQL queries to be run - the first to retrieve the count of the total number of Dinner objects (this doesn’t return the objects – rather it performs a “SELECT COUNT” statement that returns an integer), and the second to retrieve just the rows of data we need from our database for the current page of data. We can then update our DinnersController.Index() helper method to create a PaginatedList from our DinnerRepository.FindUpcomingDinners() result, and pass it to our view template: // // GET: /Dinners/ // /Dinners/Page/2 public ActionResult Index(int? page) { const int pageSize = 10; var upcomingDinners = dinnerRepository.FindUpcomingDinners(); var paginatedDinners = new PaginatedList(upcomingDinners, page ?? 0, pageSize); return View(paginatedDinners); }

We can then update the \Views\Dinners\Index.aspx view template to inherit from ViewPage> instead of ViewPage>, and then add the following code to the bottom of our view-template to show or hide next and previous navigation UI:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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<% if (Model.HasPreviousPage) { %> <%= Html.RouteLink("<<<", "UpcomingDinners", new { page=(Model.PageIndex-1) }) %> <% } %> <% if (Model.HasNextPage) { %> <%= Html.RouteLink(">>>", "UpcomingDinners", new { page = (Model.PageIndex + 1) })%> <% } %>

Notice above how we are using the Html.RouteLink() helper method to generate our hyperlinks. This method is similar to the Html.ActionLink() helper method we’ve used previously. The difference is that we are generating the URL using the “UpcomingDinners” routing rule we setup within our Global.asax file. This ensures that we’ll generate URLs to our Index() action method that have the format: /Dinners/Page/{page} – where the {page} value is a variable we are providing above based on the current PageIndex. And now when we run our application again we’ll see 10 dinners at a time in our browser:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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We also have <<< and >>> navigation UI at the bottom of the page that allows us to skip forwards and backwards over our data using search engine accessible URLs:

Side Topic: Understanding the implications of IQueryable IQueryable is a very powerful feature that enables a variety of interesting deferred execution scenarios (like paging and composition based queries). As with all powerful features, you want to be careful with how you use it and make sure it is not abused. It is important to recognize that returning an IQueryable result from your repository enables calling code to append on chained operator methods to it, and so participate in the ultimate query execution. If you do not want to provide calling code this ability, then you should return back IList, List or IEnumerable results - which contain the results of a query that has already executed. For pagination scenarios this would require you to push the actual data pagination logic into the repository method being called. In this scenario we might update our FindUpcomingDinners() finder method to have a signature that either returned a PaginatedList: PaginatedList< Dinner> FindUpcomingDinners(int pageIndex, int pageSize) { } Or return back an IList, and use a “totalCount” out param to return the total count of Dinners: IList FindUpcomingDinners(int pageIndex, int pageSize, out int totalCount) { }

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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Authentication and Authorization

Right now our NerdDinner application grants anyone visiting the site the ability to create and edit the details of any dinner. Let’s change this so that users need to register and login to the site to create new dinners, and add a restriction so that only the user who is hosting a dinner can edit it later. To enable this we’ll use authentication and authorization to secure our application.

Understanding Authentication and Authorization Authentication is the process of identifying and validating the identity of a client accessing an application. Put more simply, it is about identifying “who” the end-user is when they visit a website. ASP.NET supports multiple ways to authenticate browser users. For Internet web applications, the most common authentication approach used is called “Forms Authentication”. Forms Authentication enables a developer to author an HTML login form within their application, and then validate the username/password an end-user submits against a database or other password credential store. If the username/password combination is correct, the developer can then ask ASP.NET to issue an encrypted HTTP cookie to identify the user across future requests. We’ll be using forms authentication with our NerdDinner application. Authorization is the process of determining whether an authenticated user has permission to access a particular URL/resource or to perform some action. For example, within our NerdDinner application we’ll want to authorize that only users who are logged in can access the /Dinners/Create URL and create new Dinners. We’ll also want to add authorization logic so that only the user who is hosting a dinner can edit it – and deny edit access to all other users.

Forms Authentication and the AccountController The default Visual Studio project template for ASP.NET MVC automatically enables forms authentication when new ASP.NET MVC applications are created. It also automatically adds a pre-built account login implementation to the project – which makes it really easy to integrate security within a site. The default Site.master master page displays a “Log On” link at the top-right of the site when the user accessing it is not authenticated:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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Clicking the “Log On” link takes a user to the /Account/LogOn URL:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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Visitors who haven’t registered can do so by clicking the “Register” link – which will take them to the /Account/Register URL and allow them to enter account details:

Clicking the “Register” button will create a new user within the ASP.NET Membership system, and authenticate the user onto the site using forms authentication. When a user is logged-in, the Site.master changes the top-right of the page to output a “Welcome [username]!” message and renders a “Log Off” link instead of a “Log On” one. Clicking the “Log Off” link logs out the user:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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The above login, logout, and registration functionality is implemented within the AccountController class that was added to our project by VS when it created it. The UI for the AccountController is implemented using view templates within the \Views\Account directory:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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The AccountController class uses the ASP.NET Forms Authentication system to issue encrypted authentication cookies, and the ASP.NET Membership API to store and validate usernames/passwords. The ASP.NET Membership API is extensible and enables any password credential store to be used. ASP.NET ships with built-in membership provider implementations that store username/passwords within a SQL database, or within Active Directory. We can configure which membership provider our NerdDinner application should use by opening the “web.config” file at the root of the project and looking for the <membership> section within it. The default web.config added when the project was created registers the SQL membership provider, and configures it to use a connection-string named “ApplicationServices” to specify the database location. The default “ApplicationServices” connection string (which is specified within the section of the web.config file) is configured to use SQL Express. It points to a SQL Express database named “ASPNETDB.MDF” under the application’s “App_Data” directory. If this database doesn’t exist the first time the Membership API is used within the application, ASP.NET will automatically create the database and provision the appropriate membership database schema within it:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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If instead of using SQL Express we wanted to use a full SQL Server instance (or connect to a remote database), all we’d need to-do is to update the “ApplicationServices” connection string within the web.config file and make sure that the appropriate membership schema has been added to the database it points at. You can run the “aspnet_regsql.exe” utility within the \Windows\Microsoft.NET\Framework\v2.0.50727\ directory to add the appropriate schema for membership and the other ASP.NET application services to a database.

Authorizing the /Dinners/Create URL using the [Authorize] filter We didn’t have to write any code to enable a secure authentication and account management implementation for the NerdDinner application. Users can register new accounts with our application, and login/logout of the site. And now we can add authorization logic to the application, and use the authentication status and username of visitors to control what they can and can’t do within the site. Let’s begin by adding authorization logic to the “Create” action methods of our DinnersController class. Specifically, we will require that users accessing the /Dinners/Create URL must be logged in. If they aren’t logged in we’ll redirect them to the login page so that they can sign-in. Implementing this logic is pretty easy. All we need to-do is to add an [Authorize] filter attribute to our Create action methods like so: // // GET: /Dinners/Create [Authorize] public ActionResult Create() { ... } // // POST: /Dinners/Create [AcceptVerbs(HttpVerbs.Post), Authorize] public ActionResult Create(Dinner dinnerToCreate) { ... }

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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ASP.NET MVC supports the ability to create “action filters” that can be used to implement re-usable logic that can be declaratively applied to action methods. The [Authorize] filter is one of the built-in action filters provided by ASP.NET MVC, and it enables a developer to declaratively apply authorization rules to action methods and controller classes. When applied without any parameters (like above) the [Authorize] filter enforces that the user making the action method request must be logged in – and it will automatically redirect the browser to the login URL if they aren’t. When doing this redirect the originally requested URL is passed as a querystring argument (for example: /Account/LogOn?ReturnUrl=%2fDinners%2fCreate). The AccountController will then redirect the user back to the originally requested URL once they login. The [Authorize] filter optionally supports the ability to specify a “Users” or “Roles” property that can be used to require that the user is both logged in and within a list of allowed users or a member of an allowed security role. For example, the code below only allows two specific users, “scottgu” and “billg”, to access the /Dinners/Create URL: [Authorize(Users="scottgu,billg")] public ActionResult Create() { ... }

Embedding specific user names within code tends to be pretty un-maintainable though. A better approach is to define higher-level “roles” that the code checks against, and then to map users into the role using either a database or active directory system (enabling the actual user mapping list to be stored externally from the code). ASP.NET includes a built-in role management API as well as a built-in set of role providers (including ones for SQL and Active Directory) that can help perform this user/role mapping. We could then update the code to only allow users within a specific “admin” role to access the /Dinners/Create URL: [Authorize(Roles="admin")] public ActionResult Create() { ... }

Using the User.Identity.Name property when Creating Dinners We can retrieve the username of the currently logged-in user of a request using the User.Identity.Name property exposed on the Controller base class. Earlier when we implemented the HTTP-POST version of our Create() action method we had hardcoded the “HostedBy” property of the Dinner to a static string. We can now update this code to instead use the User.Identity.Name property, as well as automatically add an RSVP for the host creating the Dinner:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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// // POST: /Dinners/Create [AcceptVerbs(HttpVerbs.Post), Authorize] public ActionResult Create(Dinner dinner) { if (ModelState.IsValid) { try { dinner.HostedBy = User.Identity.Name; RSVP rsvp = new RSVP(); rsvp.AttendeeName = User.Identity.Name; dinner.RSVPs.Add(rsvp); dinnerRepository.Add(dinner); dinnerRepository.Save(); return RedirectToAction("Details", new { id=dinner.DinnerID }); } catch { ModelState.AddModelErrors(dinner.GetRuleViolations()); } } return View(new DinnerFormViewModel(dinner)); }

Because we have added an [Authorize] attribute to the Create() method, ASP.NET MVC ensures that the action method only executes if the user visiting the /Dinners/Create URL is logged in on the site. As such, the User.Identity.Name property value will always contain a valid username.

Using the User.Identity.Name property when Editing Dinners Let’s now add some authorization logic that restricts users so that they can only edit the properties of dinners they themselves are hosting. To help with this, we’ll first add an “IsHostedBy(username)” helper method to our Dinner object (within the Dinner.cs partial class we built earlier). This helper method returns true or false depending on whether a supplied username matches the Dinner HostedBy property, and encapsulates the logic necessary to perform a case-insensitive string comparison of them: public partial class Dinner { public bool IsHostedBy(string userName) { return HostedBy.Equals(userName, StringComparison.InvariantCultureIgnoreCase); } }

We’ll then add an [Authorize] attribute to the Edit() action methods within our DinnersController class. This will ensure that users must be logged in to request a /Dinners/Edit/[id] URL.

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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We can then add code to our Edit methods that uses the Dinner.IsHostedBy(username) helper method to verify that the logged-in user matches the Dinner host. If the user is not the host, we’ll display an “InvalidOwner” view and terminate the request. The code to do this looks like below: // // GET: /Dinners/Edit/5 [Authorize] public ActionResult Edit(int id) { Dinner dinner = dinnerRepository.GetDinner(id); if (!dinner.IsHostedBy(User.Identity.Name)) return View("InvalidOwner"); return View(new DinnerFormViewModel(dinner)); } // // POST: /Dinners/Edit/5 [AcceptVerbs(HttpVerbs.Post), Authorize] public ActionResult Edit(int id, FormCollection collection) { Dinner dinner = dinnerRepository.GetDinner(id); if (!dinner.IsHostedBy(User.Identity.Name)) return View("InvalidOwner"); try { UpdateModel(dinner); dinnerRepository.Save(); return RedirectToAction("Details", new {id = dinner.DinnerID}); } catch { ModelState.AddModelErrors(dinnerToEdit.GetRuleViolations()); return View(new DinnerFormViewModel(dinner)); } }

We can then right-click on the \Views\Dinners directory and choose the Add->View menu command to create a new “InvalidOwner” view. We’ll populate it with the below error message:

Error Accessing Dinner

Sorry - but only the host of a Dinner can edit or delete it.



Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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And now when a user attempts to edit a dinner they don’t own, they’ll get an error message:

We can repeat the same steps for the Delete() action methods within our controller to lock down permission to delete Dinners as well, and ensure that only the host of a Dinner can delete it.

Showing/Hiding Edit and Delete Links We are linking to the Edit and Delete action method of our DinnersController class from our Details URL:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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Currently we are showing the Edit and Delete action links regardless of whether the visitor to the details URL is the host of the dinner. Let’s change this so that the links are only displayed if the visiting user is the owner of the dinner. The Details() action method within our DinnersController retrieves a Dinner object and then passes it as the model object to our view template: // // GET: /Dinners/Details/5 public ActionResult Details(int id) { Dinner dinner = dinnerRepository.GetDinner(id); if (dinner == null) return View("NotFound"); return View(dinner); }

We can update our view template to conditionally show/hide the Edit and Delete links by using the Dinner.IsHostedBy() helper method like below: <% if (Model.IsHostedBy(Context.User.Identity.Name)) { %> <%= Html.ActionLink("Edit Dinner", "Edit", new { id=Model.DinnerID })%> | <%= Html.ActionLink("Delete Dinner", "Delete", new {id=Model.DinnerID})%> <% } %>

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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AJAX Enabling RSVPs Accepts

Let’s now add support for logged-in users to RSVP their interest in attending a dinner. We’ll implement this using an AJAX-based approach integrated within the dinner details page.

Indicating whether the user is RSVP’d Users can visit the /Dinners/Details/[id] URL to see details about a particular dinner:

The Details() action method is implemented like so: // // GET: /Dinners/Details/2 public ActionResult Details(int id) { Dinner dinner = dinnerRepository.GetDinner(id); if (dinner == null) return View("NotFound"); else return View(dinner); }

Our first step to implement RSVP support will be to add an “IsUserRegistered(username)” helper method to our Dinner object (within the Dinner.cs partial class we built earlier). This helper method returns true or false depending on whether the user is currently RSVP’d for the Dinner:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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public partial class Dinner { public bool IsUserRegistered(string userName) { return RSVPs.Any(r => r.AttendeeName.Equals(userName, StringComparison.InvariantCultureIgnoreCase)); } }

We can then add the following code to our Details.aspx view template to display an appropriate message indicating whether the user is registered or not for the event: <% if (Request.IsAuthenticated) { %> <% if (Model.IsUserRegistered(Context.User.Identity.Name)) { %>

You are registered for this event!

<% } else { %>

You are not registered for this event

<% } %> <% } else { %> Logon to RSVP for this event. <% } %>

And now when a user visits a Dinner they are registered for they’ll see this message:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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And when they visit a Dinner they are not registered for they’ll see the below message:

Implementing the Register Action Method Let’s now add the functionality necessary to enable users to RSVP for a dinner from the details page. To implement this, we’ll create a new “RSVPController” class by right-clicking on the \Controllers directory and choosing the Add->Controller menu command. We’ll implement a “Register” action method within the new RSVPController class that takes an id for a Dinner as an argument, retrieves the appropriate Dinner object, checks to see if the logged-in user is currently in the list of users who have registered for it, and if not adds an RSVP object for them: public class RSVPController : Controller { DinnerRepository dinnerRepository = new DinnerRepository(); // // AJAX: /Dinners/Register/1 [Authorize, AcceptVerbs(HttpVerbs.Post)] public ActionResult Register(int id) { Dinner dinner = dinnerRepository.GetDinner(id); if (!dinner.IsUserRegistered(User.Identity.Name)) { RSVP rsvp = new RSVP();

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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rsvp.AttendeeName = User.Identity.Name; dinner.RSVPs.Add(rsvp); dinnerRepository.Save(); } return Content("Thanks - we'll see you there!"); } }

Notice above how we are returning a simple string as the output of the action method. We could have embedded this message within a view template – but since it is so small we’ll just use the Content() helper method on the controller base class and return a string message like above.

Calling the Register Action Method using AJAX We’ll use AJAX to invoke the Register action method from our Details view. Implementing this is pretty easy. First we’ll add two script library references: <script src="/Scripts/MicrosoftAjax.js" type="text/javascript"> <script src="/Scripts/MicrosoftMvcAjax.js" type="text/javascript">

The first library references the core ASP.NET AJAX client-side script library. This file is approximately 24k in size (compressed) and contains core client-side AJAX functionality. The second library contains utility functions that integrate with ASP.NET MVC’s built-in AJAX helper methods (which we’ll use shortly). We can then update the view template code we added earlier so that instead of outputing a “You are not registered for this event” message, we instead render a link that when pushed performs an AJAX call that invokes our Register action method on our RSVP controller and RSVPs the user:

<% if (Request.IsAuthenticated) { %> <% if (Model.IsUserRegistered(Context.User.Identity.Name)) { %>

You are registered for this event!

<% } else { %> <%= Ajax.ActionLink( "RSVP for this event", "Register", "RSVP" new { id=Model.DinnerID }, new AjaxOptions { UpdateTargetId="rsvpmsg" }) %> <% } %> <% } else { %> Logon to RSVP for this event. <% } %>



Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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The Ajax.ActionLink() helper method used above is built-into ASP.NET MVC and is similar to the Html.ActionLink() helper method except that instead of performing a standard navigation it makes an AJAX call to the action method. Above we are calling the “Register” action method on the “RSVP” controller and passing the DinnerID as the “id” parameter to it. The final AjaxOptions parameter we are passing indicates that we want to take the content returned from the action method and update the HTML

element on the page whose id is “rsvpmsg”. And now when a user browses to a dinner they aren’t registered for yet they’ll see a link to RSVP for it:

If they click the “RSVP for this event” link they’ll make an AJAX call to the Register action method on the RSVP controller, and when it completes they’ll see an updated message like below:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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The network bandwidth and traffic involved when making this AJAX call is really lightweight. When the user clicks on the "RSVP for this event" link, a small HTTP POST network request is made to the /Dinners/Register/1 URL that looks like below on the wire: POST /Dinners/Register/49 HTTP/1.1 X-Requested-With: XMLHttpRequest Content-Type: application/x-www-form-urlencoded; charset=utf-8 Referer: http://localhost:8080/Dinners/Details/49

And the response from our Register action method is simply: HTTP/1.1 200 OK Content-Type: text/html; charset=utf-8 Content-Length: 29 Thanks - we'll see you there!

This lightweight call is fast and will work even over a slow network.

Adding a jQuery Animation The AJAX functionality we implemented works well and fast. Sometimes it can happen so fast, though, that a user might not notice that the RSVP link has been replaced with new text. To make the outcome a little more obvious we can add a simple animation to draw attention to the updates message.

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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The default ASP.NET MVC project template includes jQuery – an excellent (and very popular) open source JavaScript library that is also supported by Microsoft. jQuery provides a number of features, including a nice HTML DOM selection and effects library. To use jQuery we’ll first add a script reference to it. Because we are going to be using jQuery within a variety of places within our site, we’ll add the script reference within our Site.master master page file so that all pages can use it. <script src="/Scripts/jQuery-1.3.2.js" type="text/javascript">

Tip: make sure you have intalled the JavaScript intellisense hotfix for VS 2008 SP1 that enables richer intellisense support for JavaScript files (including jQuery). You can download it from: http://tinyurl.com/vs2008javascripthotfix Code written using JQuery often uses a global "$()" JavaScript method that retrieves one or more HTML elements using a CSS selector. For example, $(“#rsvpmsg”) selects any HTML element with the id of rsvpmsg, while $(“.something") would select all elements with the "something" CSS class name. You can also write more advanced queries like “return all of the checked radio buttons” using a selector query like: $("input[@type=radio][@checked]"). Once you've selected elements, you can call methods on them to take action, like hiding them: $("#rsvpmsg").hide(); For our RSVP scenario, we’ll define a simple JavaScript function named “AnimateRSVPMessage” that selects the “rsvpmsg”

and animates the size of its text content. The below code starts the text small and then causes it to increase over a 400 milliseconds timeframe: <script type="text/javascript"> function AnimateRSVPMessage() { $("#rsvpmsg").animate({fontSize: "1.5em"}, 400); }

We can then wire-up this JavaScript function to be called after our AJAX call successfully completes by passing its name to our Ajax.ActionLink() helper method (via the AjaxOptions “OnSuccess” event property): <%= Ajax.ActionLink( "RSVP for this event", "Register", "RSVP", new { id=Model.DinnerID }, new AjaxOptions { UpdateTargetId="rsvpmsg", OnSuccess="AnimateRSVPMessage" }) %>

And now when the “RSVP for this event” link is clicked and our AJAX call completes successfully, the content message sent back will animate and grow large:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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In addition to providing an “OnSuccess” event, the AjaxOptions object exposes OnBegin, OnFailure, and OnComplete events that you can handle (along with a variety of other properties and useful options).

Cleanup - Refactor out a RSVP Partial View Our details view template is starting to get a little long, which overtime will make it a little harder to understand. To help improve the code readability, let’s finish up by creating a partial view – RSVPStatus.ascx – that encapsulate all of the RSVP view code for our Details page. We can do this by right-clicking on the \Views\Dinners folder and then choosing the Add->View menu command. We’ll have it take a Dinner object as its strongly-typed ViewModel. We can then copy/paste the RSVP content from our Details.aspx view into it. Once we’ve done that, let’s also create another partial view – EditAndDeleteLinks.ascx - that encapsulates our Edit and Delete link view code. We’ll also have it take a Dinner object as its stronglytyped ViewModel, and copy/paste the Edit and Delete logic from our Details.aspx view into it. Our details view template can then just include two Html.RenderPartial() method calls at the bottom: <% Html.RenderPartial("RSVPStatus"); %> <% Html.RenderPartial("EditAndDeleteLinks"); %>

This makes the code cleaner to read and maintain.

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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Integrating an AJAX Map

We’ll now make our application a little more visually exciting by integrating AJAX mapping support. This will enable users who are creating, editing or viewing dinners to see the location of the dinner graphically.

Creating a Map Partial View We are going to use mapping functionality in several places within our application. To keep our code DRY we’ll encapsulate the common map functionality within a single partial template that we can re-use across multiple controller actions and views. We’ll name this partial view “map.ascx” and create it within the \Views\Dinners directory. We can create the map.ascx partial by right-clicking on the \Views\Dinners directory and choosing the Add->View menu command. We’ll name the view “Map.ascx”, check it as a partial view, and indicate that we are going to pass it a strongly-typed “Dinner” model class:

When we click the “Add” button our partial template will be created. We’ll then update the Map.ascx file to have the following content: <script src="http://dev.virtualearth.net/mapcontrol/mapcontrol.ashx?v=6.2" type="text/javascript"> <script src="/Scripts/Map.js" type="text/javascript">

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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<script type="text/javascript"> $(document).ready(function() { var latitude = <%=Model.Latitude %>; var longitude = <%=Model.Longitude %>; if ((latitude == 0) || (longitude == 0)) LoadMap(); else LoadMap(latitude, longitude, mapLoaded); }); function mapLoaded() { var title = "<%= Html.Encode(Model.Title) %>"; var address = "<%= Html.Encode(Model.Address) %>"; LoadPin(center, title, address); map.SetZoomLevel(14); }

The first <script> reference points to the Microsoft Virtual Earth 6.2 mapping library. The second <script> reference points to a map.js file that we will shortly create which will encapsulate our common Javascript mapping logic. The

element is the HTML container that Virtual Earth will use to host the map. We then have an embedded <script> block that contains two JavaScript functions specific to this view. The first function uses jQuery to wire-up a function that executes when the page is ready to run clientside script. It calls a LoadMap() helper function that we’ll define within our Map.js script file to load the virtual earth map control. The second function is a callback event handler that adds a pin to the map that identifies a location. Notice how we are using a server-side <%= %> block within the client-side script block to embed the latitude and longitude of the Dinner we want to map into the JavaScript. This is a useful technique to output dynamic values that can be used by client-side script (without requiring a separate AJAX call back to the server to retrieve the values – which makes it faster). The <%= %> blocks will execute when the view is rendering on the server – and so the output of the HTML will just end up with embedded JavaScript values (for example: var latitude = 47.64312;).

Creating a Map.js utility library Let’s now create the Map.js file that we can use to encapsulate the JavaScript functionality for our map (and implement the LoadMap and LoadPin methods above). We can do this by right-clicking on the \Scripts directory within our project, and then choose the “Add->New Item” menu command, select the JScript item, and name it “Map.js”.

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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Below is the JavaScript code we’ll add to the Map.js file that will interact with Virtual Earth to display our map and add locations pins to it for our dinners: var var var var

map = null; points = []; shapes = []; center = null;

function LoadMap(latitude, longitude, onMapLoaded) { map = new VEMap('theMap'); options = new VEMapOptions(); options.EnableBirdseye = false; // Makes the control bar less obtrusize. map.SetDashboardSize(VEDashboardSize.Small); if (onMapLoaded != null) map.onLoadMap = onMapLoaded; if (latitude != null && longitude != null) { center = new VELatLong(latitude, longitude); } map.LoadMap(center, null, null, null, null, null, null, options); } function LoadPin(LL, name, description) { var shape = new VEShape(VEShapeType.Pushpin, LL); //Make a nice Pushpin shape with a title and description shape.SetTitle("<span class=\"pinTitle\"> " + escape(name) + ""); if (description !== undefined) { shape.SetDescription("

" + escape(description) + "

"); } map.AddShape(shape); points.push(LL); shapes.push(shape); } function FindAddressOnMap(where) { var numberOfResults = 20; var setBestMapView = true; var showResults = true; map.Find("", where, null, null, null, numberOfResults, showResults, true, true, setBestMapView, callbackForLocation); } function callbackForLocation(layer, resultsArray, places, hasMore, VEErrorMessage) { clearMap(); if (places == null)

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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return; //Make a pushpin for each place we find $.each(places, function(i, item) { var description = ""; if (item.Description !== undefined) { description = item.Description; } var LL = new VELatLong(item.LatLong.Latitude, item.LatLong.Longitude); LoadPin(LL, item.Name, description); }); //Make sure all pushpins are visible if (points.length > 1) { map.SetMapView(points); } //If we've found exactly one place, that's our address. if (points.length === 1) { $("#Latitude").val(points[0].Latitude); $("#Longitude").val(points[0].Longitude); } } function clearMap() { map.Clear(); points = []; shapes = []; }

Integrating the Map with Create and Edit Forms We’ll now integrate the Map support with our existing Create and Edit scenarios. The good news is that this is pretty easy to-do, and doesn’t require us to change any of our Controller code. Because our Create and Edit views share a common “DinnerForm” partial view to implement the dinner form UI, we can add the map in one place and have both our Create and Edit scenarios use it. All we need to-do is to open the \Views\Dinners\DinnerForm.ascx partial view and update it to include our new map partial. Below is what the updated DinnerForm will look like once the map is added (note: the HTML form elements are omitted from the code snippet below for brevity): <%= Html.ValidationSummary() %> <% using (Html.BeginForm()) { %>

[HTML Form Elements Removed for Brevity]



Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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<% Html.RenderPartial("Map", Model.Dinner); %>

<script type="text/javascript"> $(document).ready(function() { $("#Address").blur(function(evt) { $("#Latitude").val(""); $("#Longitude").val(""); var address = jQuery.trim($("#Address").val()); if (address.length < 1) return; FindAddressOnMap(address); }); }); <% } %>

The DinnerForm partial above takes an object of type “DinnerFormViewModel” as its model type (because it needs both a Dinner object, as well as a SelectList to populate the dropdownlist of countries). Our Map partial just needs an object of type “Dinner” as its model type, and so when we render the map partial we are passing just the Dinner sub-property of DinnerFormViewModel to it: <% Html.RenderPartial("Map", Model.Dinner); %>

The JavaScript function we’ve added to the partial uses jQuery to attach a “blur” event to the “Address” HTML textbox. You’ve probably heard of “focus” events that fire when a user clicks or tabs into a textbox. The opposite is a “blur” event that fires when a user exits a textbox. The above event handler clears the latitude and longitude textbox values when this happens, and then plots the new address location on our map. A callback event handler that we defined within the map.js file will then update the longitude and latitude textboxes on our form using values returned by virtual earth based on the address we gave it. And now when we run our application again and click the “Host Dinner” tab we’ll see a default map displayed along with our standard Dinner form elements:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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When we type in an address, and then tab away, the map will dynamically update to display the location, and our event handler will populate the latitude/longitude textboxes with the location values:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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If we save the new dinner and then open it again for editing, we’ll find that the map location is displayed when the page loads:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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Every time the address field is changed, the map and the latitude/longitude coordinates will update. Now that the map displays the Dinner location, we can also change the Latitude and Longitude form fields from being visible textboxes to instead be hidden elements (since the map is automatically updating them each time an address is entered). To-do this we’ll switch from using the Html.TextBox() HTML helper to using the Html.Hidden()helper method:

<%= Html.Hidden("Latitude", Model.Dinner.Latitude)%> <%= Html.Hidden("Longitude", Model.Dinner.Longitude)%>



And now our forms are a little more user-friendly and avoid displaying the raw latitude/longitude (while still storing them with each Dinner in the database):

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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Integrating the Map with the Details View Now that we have the map integrated with our Create and Edit scenarios, let’s also integrate it with our Details scenario. All we need to-do is to call <% Html.RenderPartial(“map”); %> within the Details view. Below is what the source code to the complete Details view (with map integration) looks like: <%= Html.Encode(Model.Title) %>

<%= Html.Encode(Model.Title) %>

<strong>When: <%= Model.EventDate.ToShortDateString() %> <strong>@ <%= Model.EventDate.ToShortTimeString() %>

<strong>Where: <%= Html.Encode(Model.Address) %>,

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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<%= Html.Encode(Model.Country) %>

<strong>Description: <%= Html.Encode(Model.Description) %>

<strong>Organizer: <%= Html.Encode(Model.HostedBy) %> (<%= Html.Encode(Model.ContactPhone) %>)

<% Html.RenderPartial("RSVPStatus"); %> <% Html.RenderPartial("EditAndDeleteLinks"); %>

<% Html.RenderPartial("map"); %>



And now when a user navigates to a /Dinners/Details/[id] URL they’ll see details about the dinner, the location of the dinner on the map (complete with a push-pin that when hovered over displays the title of the dinner and the address of it), and have an AJAX link to RSVP for it:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

Page 156 of 186

Implementing Location Search in our Database and Repository To finish off our AJAX implementation, let’s add a Map to the home page of the application that allows users to graphically search for dinners near them.

We’ll begin by implementing support within our database and data repository layer to efficiently perform a location-based radius search for Dinners. We could use the new geospatial features of SQL 2008 to implement this, or alternatively we can use a SQL function approach that Gary Dryden discussed in article here: http://www.codeproject.com/KB/cs/distancebetweenlocations.aspx and Rob Conery blogged about using with LINQ to SQL here: http://blog.wekeroad.com/2007/08/30/linq-andgeocoding/ To implement this technique, we will open the “Server Explorer” within Visual Studio, select the NerdDinner database, and then right-click on the “functions” sub-node under it and choose to create a new “Scalar-valued function”:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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We’ll then paste in the following DistanceBetween function: CREATE FUNCTION [dbo].[DistanceBetween] (@Lat1 as real, @Long1 as real, @Lat2 as real, @Long2 as real) RETURNS real AS BEGIN DECLARE @dLat1InRad as float(53); SET @dLat1InRad = @Lat1 * (PI()/180.0); DECLARE @dLong1InRad as float(53); SET @dLong1InRad = @Long1 * (PI()/180.0); DECLARE @dLat2InRad as float(53); SET @dLat2InRad = @Lat2 * (PI()/180.0); DECLARE @dLong2InRad as float(53); SET @dLong2InRad = @Long2 * (PI()/180.0); DECLARE @dLongitude as float(53); SET @dLongitude = @dLong2InRad - @dLong1InRad; DECLARE @dLatitude as float(53); SET @dLatitude = @dLat2InRad - @dLat1InRad; /* Intermediate result a. */ DECLARE @a as float(53); SET @a = SQUARE (SIN (@dLatitude / 2.0)) + COS (@dLat1InRad) * COS (@dLat2InRad) * SQUARE(SIN (@dLongitude / 2.0)); /* Intermediate result c (great circle distance in Radians). */ DECLARE @c as real; SET @c = 2.0 * ATN2 (SQRT (@a), SQRT (1.0 - @a)); DECLARE @kEarthRadius as real; /* SET kEarthRadius = 3956.0 miles */ SET @kEarthRadius = 6376.5; /* kms */ DECLARE @dDistance as real;

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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SET @dDistance = @kEarthRadius * @c; return (@dDistance); END

We’ll then create a new table-valued function in SQL Server that we’ll call “NearestDinners”:

This “NearestDinners” table function uses the DistanceBetween helper function to return all Dinners within 100 miles of the latitude and longitude we supply it: CREATE FUNCTION [dbo].[NearestDinners] ( @lat real, @long real ) RETURNS TABLE AS RETURN SELECT Dinners.DinnerID FROM Dinners WHERE dbo.DistanceBetween(@lat, @long, Latitude, Longitude) <100

To call this function, we’ll first open up the LINQ to SQL designer by double-clicking on the NerdDinner.dbml file within our \Models directory:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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We’ll then drag the NearestDinners and DistanceBetween functions onto the LINQ to SQL designer, which will cause them to be added as methods on our LINQ to SQL NerdDinnerDataContext class:

We can then expose a “FindByLocation” query method on our DinnerRepository class that uses the NearestDinner function to return upcoming Dinners that are within 100 miles of the specified location:

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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public IQueryable FindByLocation(float latitude, float longitude) { var dinners = from dinner in FindUpcomingDinners() join i in db.NearestDinners(latitude, longitude) on dinner.DinnerID equals i.DinnerID select dinner; return dinners; }

Implementing a JSON-based AJAX Search Action Method We’ll now implement a controller action method that takes advantage of the new FindByLocation() repository method to return back a list of Dinner data that can be used to populate a map. We’ll have this action method return back the Dinner data in a JSON (JavaScript Object Notation) format so that it can be easily manipulated using JavaScript on the client. To implement this, we’ll create a new “SearchController” class by right-clicking on the \Controllers directory and choosing the Add->Controller menu command. We’ll then implement a “SearchByLocation” action method within the new SearchController class like below: public class JsonDinner { public int DinnerID public string Title public double Latitude public double Longitude public string Description public int RSVPCount }

{ { { { { {

get; get; get; get; get; get;

set; set; set; set; set; set;

} } } } } }

public class SearchController : Controller { DinnerRepository dinnerRepository = new DinnerRepository(); // // AJAX: /Search/SearchByLocation [AcceptVerbs(HttpVerbs.Post)] public ActionResult SearchByLocation(float longitude, float latitude) { var dinners = dinnerRepository.FindByLocation(latitude, longitude); var jsonDinners = from dinner in dinners select new JsonDinner { DinnerID = dinner.DinnerID, Latitude = dinner.Latitude, Longitude = dinner.Longitude, Title = dinner.Title, Description = dinner.Description, RSVPCount = dinner.RSVPs.Count }; return Json(jsonDinners.ToList()); } }

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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The SearchController’s SearchByLocation action method internally calls the FindByLocation method on DinnerRespository to get a list of nearby dinners. Rather than return the Dinner objects directly to the client, though, it instead returns JsonDinner objects. The JsonDinner class exposes a subset of Dinner properties (for example: for security reasons it doesn’t disclose the names of the people who have RSVP’d for a dinner). It also includes an RSVPCount property that doesn’t exist on Dinner– and which is dynamically calculated by counting the number of RSVP objects associated with a particular dinner. We are then using the Json() helper method on the Controller base class to return the sequence of dinners using a JSON-based wire format. JSON is a standard text format for representing simple datastructures. Below is an example of what a JSON-formatted list of two JsonDinner objects looks like when returned from our action method: [{"DinnerID":53,"Title":"Dinner with the Family","Latitude":47.64312,"Longitude":122.130609,"Description":"Fun dinner","RSVPCount":2}, {"DinnerID":54,"Title":"Another Dinner","Latitude":47.632546,"Longitude":-122.21201,"Description":"Dinner with Friends","RSVPCount":3}]

Calling the JSON-based AJAX method using jQuery We are now ready to update the home page of the NerdDinner application to use the SearchController’s SearchByLocation action method. To-do this, we’ll open the /Views/Home/Index.aspx view template and update it to have a textbox, search button, our map, and a

element named dinnerList:

Find a Dinner

Enter your location: <%= Html.TextBox("Location") %>



We can then add two JavaScript functions to the page: <script type="text/javascript"> $(document).ready(function() { LoadMap(); }); $("#search").click(function(evt) { var where = jQuery.trim($("#Location").val());

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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if (where.length < 1) return; FindDinnersGivenLocation(where); });

The first JavaScript function loads the map when the page first loads. The second JavaScript function wires up a JavaScript click event handler on the search button. When the button is pressed it calls the FindDinnersGivenLocation() JavaScript function which we’ll add to our Map.js file: function FindDinnersGivenLocation(where) { map.Find("", where, null, null, null, null, null, false, null, null, callbackUpdateMapDinners); }

This FindDinnersGivenLocation() function calls map.Find() on the Virtual Earth Control to center it on the entered location. When the virtual earth map service returns, the map.Find() method invokes the callbackUpdateMapDinners callback method we passed it as the final argument. The callbackUpdateMapDinners() method is where the real work is done. It uses jQuery’s $.post() helper method to perform an AJAX call to our SearchController’s SearchByLocation() action method – passing it the latitude and longitude of the newly centered map. It defines an inline function that will be called when the $.post() helper method completes, and the JSON-formatted dinner results returned from the SearchByLocation() action method will be passed it using a variable called “dinners”. It then does a foreach over each returned dinner, and uses the dinner’s latitude and longitude and other properties to add a new pin on the map. It also adds a dinner entry to the HTML list of dinners to the right of the map. It then wires-up a hover event for both the pushpins and the HTML list so that details about the dinner are displayed when a user hovers over them: function callbackUpdateMapDinners(layer, resultsArray, places, hasMore, VEErrorMessage) { $("#dinnerList").empty(); clearMap(); var center = map.GetCenter(); $.post("/Search/SearchByLocation", { latitude: center.Latitude, longitude: center.Longitude }, function(dinners) { $.each(dinners, function(i, dinner) { var LL = new VELatLong(dinner.Latitude, dinner.Longitude, 0, null); var RsvpMessage = ""; if (dinner.RSVPCount == 1) RsvpMessage = "" + dinner.RSVPCount + " RSVP"; else RsvpMessage = "" + dinner.RSVPCount + " RSVPs";

Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”

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// Add Pin to Map LoadPin(LL, '' + dinner.Title + '', "

" + dinner.Description + "

" + RsvpMessage); //Add a dinner to the

dinnerList on the right $('#dinnerList').append($('
• ') .attr("class", "dinnerItem") .append($('').attr("href", "/Dinners/Details/" + dinner.DinnerID) .html(dinner.Title)) .append(" ("+RsvpMessage+")")); }); // Adjust zoom to display all the pins we just added. if (points.length > 1) { map.SetMapView(points); } // Display the event's pin-bubble on hover. $(".dinnerItem").each(function(i, dinner) { $(dinner).hover( function() { map.ShowInfoBox(shapes[i]); }, function() { map.HideInfoBox(shapes[i]); } ); }); }, "json");
  
  And now when we run the application and visit the home-page we’ll be presented with a map. When we enter the name of a city the map will display the upcoming dinners near it:
  
  Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”
  
  Page 164 of 186
  
  Hovering over a dinner will display details about it:
  
  Clicking the Dinner title either in the bubble or on the right-hand side in the HTML list will navigate us to the dinner – which we can then optionally RSVP for:
  
  Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”
  
  Page 165 of 186
  
  Unit Testing
  
  Let’s develop a suite of automated unit tests that verify our NerdDinner functionality, and which will give us the confidence to make changes and improvements to the application in the future.
  
  Why Unit Test? On the drive into work one morning you have a sudden flash of inspiration about an application you are working on. You realize there is a change you can implement that will make the application dramatically better. It might be a refactoring that cleans up the code, adds a new feature, or fixes a bug. The question that confronts you when you arrive at your computer is – “how safe is it to make this improvement?” What if making the change has side effects or breaks something? The change might be simple and only take a few minutes to implement, but what if it takes hours to manually test out all of the application scenarios? What if you forget to cover a scenario and a broken application goes into production? Is making this improvement really worth all the effort? Automated unit tests can provide a safety net that enables you to continually enhance your applications, and avoid being afraid of the code you are working on. Having automated tests that quickly verify functionality enables you to code with confidence – and empower you to make improvements you might otherwise not have felt comfortable doing. They also help create solutions that are more maintainable and have a longer lifetime - which leads to a much higher return on investment. The ASP.NET MVC Framework makes it easy and natural to unit test application functionality. It also enables a Test Driven Development (TDD) workflow that enables test-first based development.
  
  NerdDinner.Tests Project When we created our NerdDinner application at the beginning of this tutorial, we were prompted with a dialog asking whether we wanted to create a unit test project to go along with the application project:
  
  Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”
  
  Page 166 of 186
  
  We kept the “Yes, create a unit test project” radio button selected – which resulted in a “NerdDinner.Tests” project being added to our solution:
  
  The NerdDinner.Tests project references the NerdDinner application project assembly, and enables us to easily add automated tests to it that verify the application.
  
  Creating Unit Tests for our Dinner Model Class Let’s add some tests to our NerdDinner.Tests project that verify the Dinner class we created when we built our model layer. We’ll start by creating a new folder within our test project called “Models” where we’ll place our modelrelated tests. We’ll then right-click on the folder and choose the Add->New Test menu command. This will bring up the “Add New Test” dialog. We’ll choose to create a “Unit Test” and name it “DinnerTest.cs”:
  
  Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”
  
  Page 167 of 186
  
  When we click the “ok” button Visual Studio will add (and open) a DinnerTest.cs file to the project:
  
  The default Visual Studio unit test template has a bunch of boiler-plate code within it that I find a little messy. Let’s clean it up to just contain the code below:
  
  Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”
  
  Page 168 of 186
  
  using using using using using
  
  System; System.Collections.Generic; System.Linq; Microsoft.VisualStudio.TestTools.UnitTesting; NerdDinner.Models;
  
  namespace NerdDinner.Tests.Models { [TestClass] public class DinnerTest { } }
  
  The [TestClass] attribute on the DinnerTest class above identifies it as a class that will contain tests, as well as optional test initialization and teardown code. We can define tests within it by adding public methods that have a [TestMethod] attribute on them. Below are the first of two tests we’ll add that exercise our Dinner class. The first test verifies that our Dinner is invalid if a new Dinner is created without all properties being set correctly. The second test verifies that our Dinner is valid when a Dinner has all properties set with valid values: [TestClass] public class DinnerTest { [TestMethod] public void Dinner_Should_Not_Be_Valid_When_Some_Properties_Incorrect() { //Arrange Dinner dinner = new Dinner() { Title = "Test title", Country = "USA", ContactPhone = "BOGUS" }; // Act bool isValid = dinner.IsValid; //Assert Assert.IsFalse(isValid); } [TestMethod] public void Dinner_Should_Be_Valid_When_All_Properties_Correct() { //Arrange Dinner dinner = new Dinner { Title = "Test title", Description = "Some description", EventDate = DateTime.Now, HostedBy = "ScottGu", Address = "One Microsoft Way", Country = "USA", Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”
  
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  ContactPhone = "425-703-8072", Latitude = 93, Longitude = -92, }; // Act bool isValid = dinner.IsValid; //Assert Assert.IsTrue(isValid); } }
  
  You’ll notice above that our test names are very explicit (and somewhat verbose). We are doing this because we might end up creating hundreds or thousands of small tests, and we want to make it easy to quickly determine the intent and behavior of each of them (especially when we are looking through a list of failures in a test runner). The test names should always be named after the functionality they are testing. Above we are using a “Noun_Should_Verb” naming pattern. We are structuring the tests using the “AAA” testing pattern – which stands for “Arrange, Act, Assert”: • • •
  
  Arrange: Setup the unit being tested Act: Exercise the unit under test and capture results Assert: Verify the behavior
  
  When we write tests we want to avoid having the individual tests do too much. Instead each test should verify only a single concept (which will make it much easier to pinpoint the cause of failures). A good guideline is to try and only have a single assert statement for each test. If you have more than one assert statement in a test method, make sure they are all being used to test the same concept. When in doubt, make another test.
  
  Running Tests Visual Studio 2008 Professional (and higher editions) includes a built-in test runner that can be used to run Visual Studio Unit Test projects within the IDE. We can select the Test->Run->All Tests in Solution menu command (or type Ctrl R, A) to run all of our unit tests. Or alternatively we can position our cursor within a specific test class or test method and use the Test->Run->Tests in Current Context menu command (or type Ctrl R, T) to run a subset of the unit tests. Let’s position our cursor within the DinnerTest class and type “Ctrl R, T” to run the two tests we just defined. When we do this a “Test Results” window will appear within Visual Studio and we’ll see the results of our test run listed within it:
  
  Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”
  
  Page 170 of 186
  
  Note: The VS test results window does not show the Class Name column by default. You can add this by right-clicking within the Test Results window and using the Add/Remove Columns menu command. Our two tests took only a fraction of a second to run – and as you can see they both passed. We can now go on and augment them by creating additional tests that verify specific rule validations, as well as cover the two helper methods - IsUserHost() and IsUserRegistered() – that we added to the Dinner class. Having all these tests in place for the Dinner class will make it much easier and safer to add new business rules and validations to it in the future. We can add our new rule logic to Dinner, and then within seconds verify that it hasn’t broken any of our previous logic functionality. Notice how using a descriptive test name makes it easy to quickly understand what each test is verifying. I recommend using the Tools->Options menu command, opening the Test Tools->Test Execution configuration screen, and checking the “Double-clicking a failed or inconclusive unit test result displays the point of failure in the test” checkbox. This will allow you to double-click on a failure in the test results window and jump immediately to the assert failure.
  
  Creating DinnersController Unit Tests Let’s now create some unit tests that verify our DinnersController functionality. We’ll start by rightclicking on the “Controllers” folder within our Test project and then choose the Add->New Test menu command. We’ll create a “Unit Test” and name it “DinnersControllerTest.cs”. We’ll create two test methods that verify the Details() action method on the DinnersController. The first will verify that a View is returned when an existing Dinner is requested. The second will verify that a “NotFound” view is returned when a non-existent Dinner is requested: [TestClass] public class DinnersControllerTest { [TestMethod] public void DetailsAction_Should_Return_View_For_ExistingDinner() { // Arrange var controller = new DinnersController(); // Act var result = controller.Details(1) as ViewResult; // Assert Assert.IsNotNull(result, "Expected View"); }
  
  Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”
  
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  [TestMethod] public void DetailsAction_Should_Return_NotFoundView_For_BogusDinner() { // Arrange var controller = new DinnersController(); // Act var result = controller.Details(999) as ViewResult; // Assert Assert.AreEqual("NotFound", result.ViewName); } }
  
  The above code compiles clean. When we run the tests, though, they both fail:
  
  If we look at the error messages, we’ll see that the reason the tests failed was because our DinnersRepository class was unable to connect to a database. Our NerdDinner application is using a connection-string to a local SQL Server Express file which lives under the \App_Data directory of the NerdDinner application project. Because our NerdDinner.Tests project compiles and runs in a different directory then the application project, the relative path location of our connection-string is incorrect. We could fix this by copying the SQL Express database file to our test project, and then add an appropriate test connection-string to it in the App.config of our test project. This would get the above tests unblocked and running. Unit testing code using a real database, though, brings with it a number of challenges. Specifically: •
  
  It significantly slows down the execution time of unit tests. The longer it takes to run tests, the less likely you are to execute them frequently. Ideally you want your unit tests to be able to be run in seconds – and have it be something you do as naturally as compiling the project.
  
  •
  
  It complicates the setup and cleanup logic within tests. You want each unit test to be isolated and independent of others (with no side effects or dependencies). When working against a real database you have to be mindful of state and reset it between tests.
  
  Let’s look at a design pattern called “dependency injection” that can help us work around these issues and avoid the need to use a real database with our tests.
  
  Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”
  
  Page 172 of 186
  
  Dependency Injection Right now DinnersController is tightly "coupled” to the DinnerRepository class. “Coupling” refers to a situation where a class explicitly relies on another class in order to work: public class DinnersController : Controller { DinnerRepository dinnerRepository = new DinnerRepository(); // // GET: /Dinners/Details/5 public ActionResult Details(int id) { Dinner dinner = dinnerRepository.FindDinner(id); if (dinner == null) return View("NotFound"); return View(dinner); }
  
  Because the DinnerRepository class requires access to a database, the tightly coupled dependency the DinnersController class has on the DinnerRepository ends up requiring us to have a database in order for the DinnersController action methods to be tested. We can get around this by employing a design pattern called “dependency injection” – which is an approach where dependencies (like repository classes that provide data access) are no longer implicitly created within classes that use them. Instead, dependencies can be explicitly passed to the class that uses them using constructor arguments. If the dependencies are defined using interfaces, we then have the flexibility to pass in “fake” dependency implementations for unit test scenarios. This enables us to create test-specific dependency implementations that do not actually require access to a database. To see this in action, let’s implement dependency injection with our DinnersController.
  
  Extracting an IDinnerRepository interface Our first step will be to create a new IDinnerRepository interface that encapsulates the repository contract our controllers require to retrieve and update Dinners. We can define this interface contract manually by right-clicking on the \Models folder, and then choosing the Add->New Item menu command and creating a new interface named IDinnerRepository.cs. Alternatively we can use the refactoring tools built-into Visual Studio Professional (and higher editions) to automatically extract and create an interface for us from our existing DinnerRepository class. To extract this interface using VS, simply position the cursor in the text editor on the DinnerRepository class, and then right-click and choose the Refactor->Extract Interface menu command:
  
  Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”
  
  Page 173 of 186
  
  This will launch the “Extract Interface” dialog and prompt us for the name of the interface to create. It will default to IDinnerRepository and automatically select all public methods on the existing DinnerRepository class to add to the interface:
  
  When we click the “ok” button, Visual Studio will add a new IDinnerRepository interface to our application:
  
  Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”
  
  Page 174 of 186
  
  public interface IDinnerRepository { IQueryable FindAllDinners(); IQueryable FindByLocation(float latitude, float longitude); IQueryable FindUpcomingDinners(); Dinner GetDinner(int id); void Add(Dinner dinner); void Delete(Dinner dinner); void Save(); }
  
  And our existing DinnerRepository class will be updated so that it implements the interface: public class DinnerRepository : IDinnerRepository { ... }
  
  Updating DinnersController to support constructor injection We’ll now update the DinnersController class to use the new interface. Currently DinnersController is hard-coded such that its “dinnerRepository” field is always a DinnerRepository instance: public class DinnersController : Controller { DinnerRepository dinnerRepository = new DinnerRepository(); ... }
  
  We’ll change it so that the “dinnerRepository” field is of type IDinnerRepository instead of DinnerRepository. We’ll then add two public DinnersController constructors. One of the constructors allows an IDinnerRepository to be passed as an argument. The other is a default constructor that uses our existing DinnerRepository implementation: public class DinnersController : Controller { IDinnerRepository dinnerRepository; public DinnersController() : this(new DinnerRepository()) { } public DinnersController(IDinnerRepository repository) { dinnerRepository = repository; } ... }
  
  Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”
  
  Page 175 of 186
  
  Because ASP.NET MVC by default creates controller classes using default constructors, our DinnersController at runtime will continue to use the DinnerRepository class to perform data access. We can now update our unit tests, though, to pass in a “fake” dinner repository implementation using the parameter constructor. This “fake” dinner repository will not require access to a real database, and instead will use in-memory sample data.
  
  Creating the FakeDinnerRepository class Let’s create a FakeDinnerRepository class. We’ll begin by creating a “Fakes” directory within our NerdDinner.Tests project and then add a new FakeDinnerRepository class to it (right-click on the folder and choose Add->New Class):
  
  We’ll update the code so that the FakeDinnerRepository class implements the IDinnerRepository interface. We can then right-click on it and choose the “Implement interface IDinnerRepository” context menu command:
  
  Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”
  
  Page 176 of 186
  
  This will cause Visual Studio to automatically add all of the IDinnerRepository interface members to our FakeDinnerRepository class with default “stub out” implementations: public class FakeDinnerRepository : IDinnerRepository { public IQueryable FindAllDinners() { throw new NotImplementedException(); } public IQueryable FindByLocation(float lat, float long){ throw new NotImplementedException(); } public IQueryable FindUpcomingDinners() { throw new NotImplementedException(); } public Dinner GetDinner(int id) { throw new NotImplementedException(); } public void Add(Dinner dinner) { throw new NotImplementedException(); } public void Delete(Dinner dinner) { throw new NotImplementedException(); } public void Save() { throw new NotImplementedException(); } }
  
  We can then update the FakeDinnerRepository implementation to work off of an in-memory List collection passed to it as a constructor argument:
  
  Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”
  
  Page 177 of 186
  
  public class FakeDinnerRepository : IDinnerRepository { private List dinnerList; public FakeDinnerRepository(List dinners) { dinnerList = dinners; } public IQueryable FindAllDinners() { return dinnerList.AsQueryable(); } public IQueryable FindUpcomingDinners() { return (from dinner in dinnerList where dinner.EventDate > DateTime.Now select dinner).AsQueryable(); } public IQueryable FindByLocation(float lat, float lon) { return (from dinner in dinnerList where dinner.Latitude == lat && dinner.Longitude == lon select dinner).AsQueryable(); } public Dinner GetDinner(int id) { return dinnerList.SingleOrDefault(d => d.DinnerID == id); } public void Add(Dinner dinner) { dinnerList.Add(dinner); } public void Delete(Dinner dinner) { dinnerList.Remove(dinner); } public void Save() { foreach (Dinner dinner in dinnerList) { if (!dinner.IsValid) throw new ApplicationException("Rule violations"); } } }
  
  We now have a fake IDinnerRepository implementation that does not require a database, and can instead work off an in-memory list of Dinner objects.
  
  Using the FakeDinnerRepository with Unit Tests Let’s return to the DinnersController unit tests that failed earlier because the database wasn’t available. We can update the test methods to use a FakeDinnerRepository populated with sample in-memory Dinner data to the DinnersController using the code below:
  
  Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”
  
  Page 178 of 186
  
  [TestClass] public class DinnersControllerTest { List CreateTestDinners() { List dinners = new List(); for (int i = 0; i < 101; i++) { Dinner sampleDinner = new Dinner() { DinnerID = i, Title = "Sample Dinner", HostedBy = "SomeUser", Address = "Some Address", Country = "USA", ContactPhone = "425-555-1212", Description = "Some description", EventDate = DateTime.Now.AddDays(i), Latitude = 99, Longitude = -99 }; dinners.Add(sampleDinner); } return dinners; } DinnersController CreateDinnersController() { var repository = new FakeDinnerRepository(CreateTestDinners()); return new DinnersController(repository); } [TestMethod] public void DetailsAction_Should_Return_View_For_Dinner() { // Arrange var controller = CreateDinnersController(); // Act var result = controller.Details(1); // Assert Assert.IsInstanceOfType(result, typeof(ViewResult)); } [TestMethod] public void DetailsAction_Should_Return_NotFoundView_For_BogusDinner() { // Arrange var controller = CreateDinnersController(); // Act var result = controller.Details(999) as ViewResult; // Assert Assert.AreEqual("NotFound", result.ViewName); } }
  
  Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”
  
  Page 179 of 186
  
  And now when we run these tests they both pass:
  
  Best of all, they take only a fraction of a second to run, and do not require any complicated setup/cleanup logic. We can now unit test all of our DinnersController action method code (including listing, paging, details, create, update and delete) without ever needing to connect to a real database. Side Topic: Dependency Injection Frameworks Performing manual dependency injection (like we are above) works fine, but does become harder to maintain as the number of dependencies and components in an application increases. Several dependency injection frameworks exist for .NET that can help provide even more dependency management flexibility. These frameworks, also sometimes called “Inversion of Control” (IoC) containers, provide mechanisms that enable an additional level of configuration support for specifying and passing dependencies to objects at runtime (most often using constructor injection). Some of the more popular OSS Dependency Injection / IOC frameworks in .NET include: AutoFac, Ninject, Spring.NET, StructureMap, and Windsor. ASP.NET MVC exposes extensibility APIs that enable developers to participate in the resolution and instantiation of controllers, and which enables Dependency Injection / IoC frameworks to be cleanly integrated within this process. Using a DI/IOC framework would also enable us to remove the default constructor from our DinnersController – which would completely remove the coupling between it and the DinnerRepository.s We won’t be using a dependency injection / IOC framework with our NerdDinner application. But it is something we could consider for the future if the NerdDinner code-base and capabilities grew.
  
  Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”
  
  Page 180 of 186
  
  Creating Edit Action Unit Tests Let’s now create some unit tests that verify the Edit functionality of the DinnersController. We’ll start by testing the HTTP-GET version of our Edit action: // // GET: /Dinners/Edit/5 [Authorize] public ActionResult Edit(int id) { Dinner dinner = dinnerRepository.GetDinner(id); if (!dinner.IsHostedBy(User.Identity.Name)) return View("InvalidOwner"); return View(new DinnerFormViewModel(dinner)); }
  
  We’ll create a test that verifies that a View backed by a DinnerFormViewModel object is rendered back when a valid dinner is requested: [TestMethod] public void EditAction_Should_Return_View_For_ValidDinner() { // Arrange var controller = CreateDinnersController(); // Act var result = controller.Edit(1) as ViewResult; // Assert Assert.IsInstanceOfType(result.ViewData.Model, typeof(DinnerFormViewModel)); }
  
  When we run the test, though, we’ll find that it fails because a null reference exception is thrown when the Edit method accesses the User.Identity.Name property to perform the Dinner.IsHostedBy() check. The User object on the Controller base class encapsulates details about the logged-in user, and is populated by ASP.NET MVC when it creates the controller at runtime. Because we are testing the DinnersController outside of a web-server environment, the User object isn’t set (hence the null reference exception).
  
  Mocking the User.Identity.Name property Mocking frameworks make testing easier by enabling us to dynamically create fake versions of dependent objects that support our tests. For example, we can use a mocking framework in our Edit action test to dynamically create a User object that our DinnersController can use to lookup a simulated username. This will avoid a null reference from being thrown when we run our test.
  
  Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”
  
  Page 181 of 186
  
  There are many .NET mocking frameworks that can be used with ASP.NET MVC (you can see a list of them here: http://www.mockframeworks.com/). For testing our NerdDinner application we’ll use an open source mocking framework called “Moq”, which can be downloaded for free from http://www.mockframeworks.com/moq. Once downloaded, we’ll add a reference in our NerdDinner.Tests project to the Moq.dll assembly:
  
  We’ll then add an overloaded “CreateDinnersControllerAs(username)” helper method to our test class that takes a username as a parameter, and which then “mocks” the User.Identity.Name property on the DinnersController instance:
  
  Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”
  
  Page 182 of 186
  
  DinnersController CreateDinnersControllerAs(string userName) { var mock = new Mock(); mock.SetupGet(p => p.HttpContext.User.Identity.Name).Returns(userName); mock.SetupGet(p => p.HttpContext.Request.IsAuthenticated).Returns(true); var controller = CreateDinnersController(); controller.ControllerContext = mock.Object; return controller; }
  
  Above we are using Moq to create a Mock object that fakes a ControllerContext object (which is what ASP.NET MVC passes to Controller classes to expose runtime objects like User, Request, Response, and Session). We are calling the “SetupGet” method on the Mock to indicate that the HttpContext.User.Identity.Name property on ControllerContext should return the username string we passed to the helper method. We can mock any number of ControllerContext properties and methods. To illustrate this I’ve also added a SetupGet() call for the Request.IsAuthenticated property (which isn’t actually needed for the tests below – but which helps illustrate how you can mock Request properties). When we are done we assign an instance of the ControllerContext mock to the DinnersController our helper method returns. We can now write unit tests that use this helper method to test Edit scenarios involving different users: [TestMethod] public void EditAction_Should_Return_EditView_When_ValidOwner() { // Arrange var controller = CreateDinnersControllerAs("SomeUser"); // Act var result = controller.Edit(1) as ViewResult; // Assert Assert.IsInstanceOfType(result.ViewData.Model, typeof(DinnerFormViewModel)); } [TestMethod] public void EditAction_Should_Return_InvalidOwnerView_When_InvalidOwner() { // Arrange var controller = CreateDinnersControllerAs("NotOwnerUser"); // Act var result = controller.Edit(1) as ViewResult; // Assert Assert.AreEqual(result.ViewName, "InvalidOwner"); }
  
  Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”
  
  Page 183 of 186
  
  And now when we run the tests they pass:
  
  Testing UpdateModel() scenarios We’ve created tests that cover the HTTP-GET version of the Edit action. Let’s now create some tests that verify the HTTP-POST version of the Edit action: // // POST: /Dinners/Edit/5 [AcceptVerbs(HttpVerbs.Post), Authorize] public ActionResult Edit (int id, FormCollection collection) { Dinner dinner = dinnerRepository.GetDinner(id); if (!dinner.IsHostedBy(User.Identity.Name)) return View("InvalidOwner"); try { UpdateModel(dinner); dinnerRepository.Save(); return RedirectToAction("Details", new { id=dinner.DinnerID }); } catch { ModelState.AddModelErrors(dinner.GetRuleViolations()); return View(new DinnerFormViewModel(dinner)); } }
  
  The interesting new testing scenario for us to support with this action method is its usage of the UpdateModel() helper method on the Controller base class. We are using this helper method to bind form-post values to our Dinner object instance. Below are two tests that demonstrates how we can supply form posted values for the UpdateModel() helper method to use. We’ll do this by creating and populating a FormCollection object, and then assign it to the “ValueProvider” property on the Controller.
  
  Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”
  
  Page 184 of 186
  
  The first test verifies that on a successful save the browser is redirected to the details action. The second test verifies that when invalid input is posted the action redisplays the edit view again with an error message. public void EditAction_Should_Redirect_When_Update_Successful() { // Arrange var controller = CreateDinnersControllerAs("SomeUser"); var formValues = new FormCollection() { { "Title", "Another value" }, { "Description", "Another description" } }; controller.ValueProvider = formValues.ToValueProvider(); // Act var result = controller.Edit(1, formValues) as RedirectToRouteResult; // Assert Assert.AreEqual("Details", result.RouteValues["Action"]); }
  
  [TestMethod] public void EditAction_Should_Redisplay_With_Errors_When_Update_Fails() { // Arrange var controller = CreateDinnersControllerAs("SomeUser"); var formValues = new FormCollection() { { "EventDate", "Bogus date value!!!"} }; controller.ValueProvider = formValues.ToValueProvider(); // Act var result = controller.Edit(1, formValues) as ViewResult; // Assert Assert.IsNotNull(result, "Expected redisplay of view"); Assert.IsTrue(result.ViewData.ModelState.Count > 0, "Expected errors"); }
  
  Testing Wrap-Up We’ve covered the core concepts involved in unit testing controller classes. We can use these techniques to easily create hundreds of simple tests that verify the behavior of our application. Because our controller and model tests do not require a real database, they are extremely fast and easy to run. We’ll be able to execute hundreds of automated tests in seconds, and immediately get feedback as to whether a change we made broke something. This will help provide us the confidence to continually improve, refactor, and refine our application.
  
  Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”
  
  Page 185 of 186
  
  We covered testing as the last topic in this chapter – but not because testing is something you should do at the end of a development process! On the contrary, you should write automated tests as early as possible in your development process. Doing so enables you to get immediate feedback as you develop, helps you think thoughtfully about your application’s use case scenarios, and guides you to design your application with clean layering and coupling in mind. A later chapter in this book will discuss Test Driven Development (TDD), and how to use it with ASP.NET MVC. TDD is an iterative coding practice where you first write the tests that your resulting code will satisfy. With TDD you begin each feature by creating a test that verifies the functionality you are about to implement. Writing the unit test first helps ensure that you clearly understand the feature and how it is supposed to work. Only after the test is written (and you have verified that it fails) do you then implement the actual functionality the test verifies. Because you’ve already spent time thinking about the use case of how the feature is supposed to work, you will have a better understanding of the requirements and how best to implement them. When you are done with the implementation you can re-run the test – and get immediate feedback as to whether the feature works correctly. We'll cover TDD more in Chapter 10.
  
  Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”
  
  Page 186 of 186
  
  NerdDinner Wrap Up
  
  Our initial version of our NerdDinner application is now complete and ready to deploy on the web.
  
  We used a broad set of ASP.NET MVC features to build NerdDinner. Hopefully the process of developing it shed some light on how the core ASP.NET MVC features work, and provided context on how these features integrate together within an application. The following chapters will go into more depth on ASP.NET MVC and discuss its features in detail.
  
  Chapter 1 is licensed under the terms of Creative Commons Attribution No Derivatives 3.0 license and may be redistributed according to those terms with the following attribution: “Chapter 1 “NerdDinner” from Professional ASP.NET MVC 1.0 written by Rob Conery et al published by Wrox (ISBN: 978-0-470-38461-9) may be redistributed under the terms of Creative Commons Attribution No Derivatives 3.0 license. The original copy is available at http://tinyurl.com/aspnetmvc. The complete book Professional ASP.NET MVC 1.0 is copyright 2009 by Wiley Publishing Inc and may not be redistributed without permission.”
  
  A
  
  Creative Commons License CREATIVE COMMONS CORPORATION IS NOT A LAW FIRM AND DOES NOT PROVIDE LEGAL SERVICES. DISTRIBUTION OF THIS LICENSE DOES NOT CREATE AN ATTORNEY-CLIENT RELATIONSHIP. CREATIVE COMMONS PROVIDES THIS INFORMATION ON AN “AS-IS” BASIS. CREATIVE COMMONS MAKES NO WARRANTIES REGARDING THE INFORMATION PROVIDED, AND DISCLAIMS LIABILITY FOR DAMAGES RESULTING FROM ITS USE.
  
  License THE WORK (AS DEFINED BELOW) IS PROVIDED UNDER THE TERMS OF THIS CREATIVE COMMONS PUBLIC LICENSE (“CCPL” OR “LICENSE”). THE WORK IS PROTECTED BY COPYRIGHT AND/OR OTHER APPLICABLE LAW. ANY USE OF THE WORK OTHER THAN AS AUTHORIZED UNDER THIS LICENSE OR COPYRIGHT LAW IS PROHIBITED. BY EXERCISING ANY RIGHTS TO THE WORK PROVIDED HERE, YOU ACCEPT AND AGREE TO BE BOUND BY THE TERMS OF THIS LICENSE. TO THE EXTENT THIS LICENSE MAY BE CONSIDERED TO BE A CONTRACT, THE LICENSOR GRANTS YOU THE RIGHTS CONTAINED HERE IN CONSIDERATION OF YOUR ACCEPTANCE OF SUCH TERMS AND CONDITIONS.
  
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  3/2/09 8:08:48 AM
  
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  “Original Author” means, in the case of a literary or artistic work, the individual, individuals, entity or entities who created the Work or if no individual or entity can be identified, the publisher; and in addition (i) in the case of a performance the actors, singers, musicians, dancers, and other persons who act, sing, deliver, declaim, play in, interpret or otherwise perform literary or artistic works or expressions of folklore; (ii) in the case of a phonogram the producer being the person or legal entity who first fixes the sounds of a performance or other sounds; and, (iii) in the case of broadcasts, the organization that transmits the broadcast.
  
  
  
  f.
  
  “Work” means the literary and/or artistic work offered under the terms of this License including without limitation any production in the literary, scientific and artistic domain, whatever may be the mode or form of its expression including digital form, such as a book, pamphlet and other writing; a lecture, address, sermon or other work of the same nature; a dramatic or dramatico-musical work; a choreographic work or entertainment in dumb show; a musical composition with or without words; a cinematographic work to which are assimilated works expressed by a process analogous to cinematography; a work of drawing, painting, architecture, sculpture, engraving or lithography; a photographic work to which are assimilated works expressed by a process analogous to photography; a work of applied art; an illustration, map, plan, sketch or three-dimensional work relative to geography, topography, architecture or science; a performance; a broadcast; a phonogram; a compilation of data to the extent it is protected as a copyrightable work; or a work performed by a variety or circus performer to the extent it is not otherwise considered a literary or artistic work.
  
  
  
  g.
  
  “You” means an individual or entity exercising rights under this License who has not previously violated the terms of this License with respect to the Work, or who has received express permission from the Licensor to exercise rights under this License despite a previous violation.
  
  
  
  h.
  
  “Publicly Perform” means to perform public recitations of the Work and to communicate to the public those public recitations, by any means or process, including by wire or wireless means or public digital performances; to make available to the public Works in such a way that members of the public may access these Works from a place and at a place
  
  2
  
  84619bapp01w.indd 2
  
  3/2/09 8:08:48 AM
  
  Appendix A: Creative Commons License individually chosen by them; to perform the Work to the public by any means or process and the communication to the public of the performances of the Work, including by public digital performance; to broadcast and rebroadcast the Work by any means including signs, sounds or images.
  
  i.
  
  “Reproduce” means to make copies of the Work by any means including without limitation by sound or visual recordings and the right of fixation and reproducing fixations of the Work, including storage of a protected performance or phonogram in digital form or other electronic medium.
  
  
  
  2.
  
  Fair Dealing Rights. Nothing in this License is intended to reduce, limit, or restrict any uses free from copyright or rights arising from limitations or exceptions that are provided for in connection with the copyright protection under copyright law or other applicable laws.
  
  
  
  3.
  
  License Grant. Subject to the terms and conditions of this License, Licensor hereby grants You a worldwide, royalty-free, non-exclusive, perpetual (for the duration of the applicable copyright) license to exercise the rights in the Work as stated below:
  
  a.
  
  to Reproduce the Work, to incorporate the Work into one or more Collections, and to Reproduce the Work as incorporated in the Collections; and,
  
  
  
  b. c.
  
  to Distribute and Publicly Perform the Work including as incorporated in Collections.
  
  
  
  For the avoidance of doubt:
  
  i.
  
  Non-waivable Compulsory License Schemes. In those jurisdictions in which the right to collect royalties through any statutory or compulsory licensing scheme cannot be waived, the Licensor reserves the exclusive right to collect such royalties for any exercise by You of the rights granted under this License;
  
  
  
  ii.
  
  Waivable Compulsory License Schemes. In those jurisdictions in which the right to collect royalties through any statutory or compulsory licensing scheme can be waived, the Licensor waives the exclusive right to collect such royalties for any exercise by You of the rights granted under this License; and,
  
  
  
  iii.
  
  Voluntary License Schemes. The Licensor waives the right to collect royalties, whether individually or, in the event that the Licensor is a member of a collecting society that administers voluntary licensing schemes, via that society, from any exercise by You of the rights granted under this License.
  
  The above rights may be exercised in all media and formats whether now known or hereafter devised. The above rights include the right to make such modifications as are technically necessary to exercise the rights in other media and formats, but otherwise you have no rights to make Adaptations. Subject to Section 8(f), all rights not expressly granted by Licensor are hereby reserved.
  
  4.
  
  Restrictions. The license granted in Section 3 above is expressly made subject to and limited by the following restrictions:
  
  a.
  
  You may Distribute or Publicly Perform the Work only under the terms of this License. You must include a copy of, or the Uniform Resource Identifier (URI) for, this License with every copy of the Work You Distribute or Publicly Perform. You may not offer or impose any terms on the Work that restrict the terms of this License or the ability of the recipient of the Work to exercise the rights granted to that recipient under the terms of the License. You may not sublicense the Work. You must keep intact all notices that
  
  3
  
  84619bapp01w.indd 3
  
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  Appendix A: Creative Commons License refer to this License and to the disclaimer of warranties with every copy of the Work You Distribute or Publicly Perform. When You Distribute or Publicly Perform the Work, You may not impose any effective technological measures on the Work that restrict the ability of a recipient of the Work from You to exercise the rights granted to that recipient under the terms of the License. This Section 4(a) applies to the Work as incorporated in a Collection, but this does not require the Collection apart from the Work itself to be made subject to the terms of this License. If You create a Collection, upon notice from any Licensor You must, to the extent practicable, remove from the Collection any credit as required by Section 4(b), as requested.
  
  
  
  
  
  b.
  
  If You Distribute, or Publicly Perform the Work or Collections, You must, unless a request has been made pursuant to Section 4(a), keep intact all copyright notices for the Work and provide, reasonable to the medium or means You are utilizing: (i) the name of the Original Author (or pseudonym, if applicable) if supplied, and/or if the Original Author and/or Licensor designate another party or parties (e.g., a sponsor institute, publishing entity, journal) for attribution (“Attribution Parties”) in Licensor’s copyright notice, terms of service or by other reasonable means, the name of such party or parties; (ii) the title of the Work if supplied; (iii) to the extent reasonably practicable, the URI, if any, that Licensor specifies to be associated with the Work, unless such URI does not refer to the copyright notice or licensing information for the Work. The credit required by this Section 4(b) may be implemented in any reasonable manner; provided, however, that in the case of a Collection, at a minimum such credit will appear, if a credit for all contributing authors of the Collection appears, then as part of these credits and in a manner at least as prominent as the credits for the other contributing authors. For the avoidance of doubt, You may only use the credit required by this Section for the purpose of attribution in the manner set out above and, by exercising Your rights under this License, You may not implicitly or explicitly assert or imply any connection with, sponsorship or endorsement by the Original Author, Licensor and/or Attribution Parties, as appropriate, of You or Your use of the Work, without the separate, express prior written permission of the Original Author, Licensor and/or Attribution Parties.
  
  
  
  c.
  
  Except as otherwise agreed in writing by the Licensor or as may be otherwise permitted by applicable law, if You Reproduce, Distribute or Publicly Perform the Work either by itself or as part of any Collections, You must not distort, mutilate, modify or take other derogatory action in relation to the Work which would be prejudicial to the Original Author’s honor or reputation.
  
  5.
  
  Representations, Warranties and Disclaimer UNLESS OTHERWISE MUTUALLY AGREED TO BY THE PARTIES IN WRITING, LICENSOR OFFERS THE WORK AS-IS AND MAKES NO REPRESENTATIONS OR WARRANTIES OF ANY KIND CONCERNING THE WORK, EXPRESS, IMPLIED, STATUTORY OR OTHERWISE, INCLUDING, WITHOUT LIMITATION, WARRANTIES OF TITLE, MERCHANTIBILITY, FITNESS FOR A PARTICULAR PURPOSE, NONINFRINGEMENT, OR THE ABSENCE OF LATENT OR OTHER DEFECTS, ACCURACY, OR THE PRESENCE OF ABSENCE OF ERRORS, WHETHER OR NOT DISCOVERABLE. SOME JURISDICTIONS DO NOT ALLOW THE EXCLUSION OF IMPLIED WARRANTIES, SO SUCH EXCLUSION MAY NOT APPLY TO YOU.
  
  
  
  6.
  
  Limitation on Liability. EXCEPT TO THE EXTENT REQUIRED BY APPLICABLE LAW, IN NO EVENT WILL LICENSOR BE LIABLE TO YOU ON ANY LEGAL THEORY FOR ANY SPECIAL, INCIDENTAL, CONSEQUENTIAL, PUNITIVE OR EXEMPLARY DAMAGES ARISING OUT OF THIS LICENSE OR THE USE OF THE WORK, EVEN IF LICENSOR HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
  
  4
  
  84619bapp01w.indd 4
  
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  Appendix A: Creative Commons License
  
  
  
  7.
  
  Termination
  
  a.
  
  This License and the rights granted hereunder will terminate automatically upon any breach by You of the terms of this License. Individuals or entities who have received Collections from You under this License, however, will not have their licenses terminated provided such individuals or entities remain in full compliance with those licenses. Sections 1, 2, 5, 6, 7, and 8 will survive any termination of this License.
  
  
  
  b.
  
  Subject to the above terms and conditions, the license granted here is perpetual (for the duration of the applicable copyright in the Work). Notwithstanding the above, Licensor reserves the right to release the Work under different license terms or to stop distributing the Work at any time; provided, however that any such election will not serve to withdraw this License (or any other license that has been, or is required to be, granted under the terms of this License), and this License will continue in full force and effect unless terminated as stated above.
  
  8.
  
  Miscellaneous
  
  a.
  
  Each time You Distribute or Publicly Perform the Work or a Collection, the Licensor offers to the recipient a license to the Work on the same terms and conditions as the license granted to You under this License.
  
  
  
  b.
  
  If any provision of this License is invalid or unenforceable under applicable law, it shall not affect the validity or enforceability of the remainder of the terms of this License, and without further action by the parties to this agreement, such provision shall be reformed to the minimum extent necessary to make such provision valid and enforceable.
  
  
  
  c.
  
  No term or provision of this License shall be deemed waived and no breach consented to unless such waiver or consent shall be in writing and signed by the party to be charged with such waiver or consent.
  
  
  
  d.
  
  This License constitutes the entire agreement between the parties with respect to the Work licensed here. There are no understandings, agreements or representations with respect to the Work not specified here. Licensor shall not be bound by any additional provisions that may appear in any communication from You. This License may not be modified without the mutual written agreement of the Licensor and You.
  
  
  
  e.
  
  The rights granted under, and the subject matter referenced, in this License were drafted utilizing the terminology of the Berne Convention for the Protection of Literary and Artistic Works (as amended on September 28, 1979), the Rome Convention of 1961, the WIPO Copyright Treaty of 1996, the WIPO Performances and Phonograms Treaty of 1996 and the Universal Copyright Convention (as revised on July 24, 1971). These rights and subject matter take effect in the relevant jurisdiction in which the License terms are sought to be enforced according to the corresponding provisions of the implementation of those treaty provisions in the applicable national law. If the standard suite of rights granted under applicable copyright law includes additional rights not granted under this License, such additional rights are deemed to be included in the License; this License is not intended to restrict the license of any rights under applicable law.
  
  5
  
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  Appendix A: Creative Commons License Creative Commons Notice Creative Commons is not a party to this License, and makes no warranty whatsoever in connection with the Work. Creative Commons will not be liable to You or any party on any legal theory for any damages whatsoever, including without limitation any general, special, incidental or consequential damages arising in connection to this license. Notwithstanding the foregoing two (2) sentences, if Creative Commons has expressly identified itself as the Licensor hereunder, it shall have all rights and obligations of Licensor. Except for the limited purpose of indicating to the public that the Work is licensed under the CCPL, Creative Commons does not authorize the use by either party of the trademark “Creative Commons” or any related trademark or logo of Creative Commons without the prior written consent of Creative Commons. Any permitted use will be in compliance with Creative Commons’ then-current trademark usage guidelines, as may be published on its website or otherwise made available upon request from time to time. For the avoidance of doubt, this trademark restriction does not form part of this License. Creative Commons may be contacted at http://creativecommons.org/.
  
  6
  
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  Hanselman-Book-Ad-3-6-09-OUTLINES_color.pdf
  
  3/6/09
  
  8:52:16 AM
  
  There’s more than one way to build an ASP.NET Application For developers who like to peel away layers of abstraction and get their hands closer to the metal, the ASP.NET MVC framework might be for you. For developers who are extremely particular about how their frameworks should be put together, ASP.NET MVC is also extremely extensible, allowing nearly any part of it to be customized or even swapped out entirely in favor of something that fits the developer’s own tastes. Written by members of the ASP.NET team, this book will show readers:
  
  Rob Conery, Scott Hanselman, Phil Haack, Scott Guthrie
  
  
  
  The toolsets and technologies that complement MVC, such as SubSonic, LINQ, jQuery, and REST
  
  
  
  The structure of a standard ASP.NET MVC application
  
  
  
  Advanced routing strategies and advanced techniques for extending the framework
  
  
  
  How to share data between ASP.NET MVC and ASP.NET Web Forms
  
  
  
  How to create a compelling, real-world application by following along with the authors as they create the foundation for Nerddinner.com
  
  ISBN 978-0-470-38461-9, $49.99 US
  
  Pre-order your copy today at your favorite bookseller. Amazon.com
  
  BarnesandNoble.com Borders.com
  
  Bookpool.com
  
  

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